Don't let the rarity of this fool you, this isn't quite as tough as you would have initially thought. You can farm lives for hours on end so losing from deaths is fairly unlikely, if you decide to grind them out for a couple hours.
I had only played through the game about 2 times fully before attempting this, and spent a good couple hours on bosses and the areas i struggled with before my final successful attempt at this. i am in no way an expert at the game, but a bit of practice goes a long way.
I'd say it took me about 10 hours all in all to get this (7 on the actual run, because this mad person thought many hundreds of lives was a good idea, and 3 practicing) - I am in no way very experienced at this game and although i found this to be a challenge it was also very achievable.
By this point i'm assuming you know enough about the game to know where the cameo locations and characters are and have at least beaten the game once, if you don't then this guide is waaaaaaaaaaay over your head.
This is a rough guide of what to do, this is not a walkthrough and for the most part knowledge of the game is assumed. Less obvious shortcuts and things to look out for that i have found are written down but for the most part it's just general tips and advice.
With that out of the way, go grab yourself a cup of tea and your favorite turbo controller / input wrapper and settle down for a long read.
First off, what this mode changes from Old School and Normal Mode.
2 Beers - Right off the bat, 2 beers has a drastic change to the game, as certain areas now cannot be rushed through with abandon, meaning the gameplay slows down quite a bit, and that hard areas become harder, and bosses become much, much much harder.
5 Lives - For the most part this is irrelevant, you can still farm lives to your heart's content. Admittedly the 5 lives means you have to be pretty consistent in the early game stage before unlocking mike.
3 Continues - pretty irrelevant as you can farm lives
Weak Weapons - every weapon does 30% less damage, This slows the game down quite a bit, but other than boss fights this doesn't cause significant problems. For boss fights this becomes a nightmare.
Strong enemies - Arguably the worst change here as bosses attack even faster, and move even faster (combine this with the weaker weapons and only 2 beers and you realise what a huge jump in difficulty boss fights are on this difficulty. So much so The devil boss in Thy Farts Consumed, The Hell Level, moves so fast that you cannot avoid being hit, or actually deal damage to it without the super scope). In terms of gameplay on levels, it doesn't make much of a difference, some of the larger enemies such as the pogo man in beat em and eat em and projectile firing enemies attack faster but for the most part it's not a problem.
Onto the route, at least i used, for playing the game. This is generally based on the levels that gave me the most difficulty. You can make your own route but i'd advise you have all the characters before you attempt the harder levels.
Future Fuckballs 2010
Dungeons & Dickholes
Thy Farts Consumed (for grinding your lives)
Beat it and Eat it
Thy Farts Consumed (for reals this time)
Assholevania
Happyfun Candytime
Blizzard of Balls
Boo! Haunted House
Laughin' Jokin' Numbnuts
And from that route i'll break down the levels.
Future Fuckballs 2010 - Difficulty 1/5. Not very challenging, one tricky jump
Realistically this should be a cakewalk at this point in the game, the lasers aren't particularly likely to kill you once you know how to play the stage, however as your weapons are weaker you may need to take your time when killing the ROB Robots, the main strategy for this stage is that you're going to want to pick up the two glitch gremlins and save them for the very end of the level.
Play it normally up until the third ladder (The ladder leading up to the platform where the glitch gremlin is, and the one where the ROB Robot can actually stand on top of the ladder when moving) and instead of climbing the ladder and risking damage, you can jump up to the platform just to the right, saving you the risk of taking damage.
When you get the glitch gremlin, instead of using him immediately jump to the block to the right, the ROBS can't hit you there and you can duck down and kill them without risk.
It's best to jump up onto the ladder when you get to the sphere circling it, you can go to the shit pickle if you're desperate for the extra life, but getting back is fairly risky.
When you get to the guitar guy, take the moving block path below you and collect an easy extra life, and the beer should you have taken damage, before continuing the stage
At the first disappearing blocks part, don't waste time killing the 2 flying enemies that spawn, they move in an arc, and as long as you keep jumping, you will be able to jump over them without risk, shooting them takes too long on the difficulty and you'll likely either get hit by them, or fall to your doom
After the moving platforms part make sure you avoid the supermechadethchrist3000 pickup, this is pretty tricky, my best advice is to land on the far right edge of the platform. IF you accidentally pick it up then you're going to have to reset the level, i found that lining up my foot with the death block on the platform below it, running to the right and jumping from the edge just as the death sphere is at the top of it's arc, and then jumping all the way to the right was the most consistent way of getting this.
The two pictures below should show you what i mean.
(Where to line up from)
(When and where to jump)
(Where to land) - You will have to immediately jump to the other platform when you land as you will either die, or pick up the powerup otherwise
Grab the life after the second disappearing platform part
Once you're on the silver surfer board it's plain sailing
For the boss, your main goal is to destroy all the spinning heads as ast as possible (There's 2 beers in the fight so you can be pretty reckless in doing so) and when she goes into her second stage use the glitch gremlin to freeze here in place for an easy kill. (You can do it all in one use of the glitch gremlin, but it's best to stay safe and keep two) - If you think one is enough then i'd advise you use the other glitch gremlin to stop the death sphere when getting past the supermechadeathchrist pickup
Dungeons & Dickholes - Difficulty 5/5. The limited life stock at the beginning and the, in my opinion mandatory, requirement to keep the super scope through the unforgiving flying section makes one of the hardest levels
Continue as normal until you get to the ladder taking you into the labyrinth, head all the way to the right when you land, the floor will collapse (keep holding right) and you will skip the first key area.
There are no major changes up until you get mike, you will only have 7 lives to do this part of the stage, for now at least, the only area that gave me problems was the fireball and death block area just after the disappearing blocks, you only have 2 beers so it's far less lenient than on easier difficulties. This is something you really need to practice for consistency.
You now have two choices, finish the level, or grind for lives and come back here when you're stocked up. (I always chose to grind for lives because 10 or so lives isn't enough for the 'fun' later on in the stage)
After obtaining the key it is much safer to use mike, jump up, and hit the switch with your sword than it is to jump and use guitar man.
After unlocking the door with the key, and you get to the area with the disappearing platforms, switch to mike and destroy the wall for a small shortcut, not super useful like the key skip earlier, but i've been unlucky enough to get trapped by the bat that spawns just after it more than once.
Don't worry about the first superscope when getting the key to exit the labyrinth, this isn't the one you need so you can take the hit when getting the key (This is something you really should practice, as the lower stock of beer makes this part a much greater challenge)
Once you get outside, switch to mike, to break the wall to the left and collect the superscope and extra lives.
Now for one of the worst parts of the game, flying the gargoyle without getting hit.
The main advice i can give is stay to the bottom third of the screen to avoid the bubbles, then after the second deathblock wall fly immediately upto the top, making sure to not get hit by the bird. Then staying in the top third of the screen to avoid the fireballs.
If you've made it this far, firstly congratulations on beating one of the worst platforming part of the game, and secondly, for the love of god don't get hit by the boss.
With a turbo controller and the superscope you should be able to kill the boss before he fires at you, and should easily be able to kill it.
If you lose your superscope then good luck beating him, i'd recommend restarting the stage and trying again, it is possible to beat him without it, but it's significantly more challenging (like 20-30 minutes of attempts when i did it) to do so, it's generally faster and easier to restart the stage and do it over again instead.
Beat it and eat it - 3/5 with the superscope 4/5 without.
Generally no real change in this level from how you would play it in normal difficulty, there are a few things i'd recommend doing.
When you get to the area with the glitch gremlin pickup, collect the glitch gremlin pickup, climb back up the ladder, switch to mike, jump over the death block to get the 1up and then switch to the bullshit man to kill the first pogo man enemy. This makes the next part of the level considerably easier as you don't risk being hit by enemies.
Use the first glitch gremlin to freeze the stars in place when bouncing on the breasts below where you previously were (If you die you can climb back up the ladder and get another glitch gremlin power up and try again)
Be incredibly weary of the witch that spawns she can very easily catch you off guard and kill you.
Use the second glitch gremlin just before landing on the platform with the superscope. I found that Killing her is very inconsistent, and that using the glitch gremlin makes it considerably easier.
Speaking of superscopes you'll probably assume i want you to keep it till the boss by now. It's fairly easy to do unlike on Dungeons & Dickholes. The most consistent way to get past the starting death star is to jump on the platform below the death blocks, then jump straight across to the other one and quickly move onto the breasts. A little bit of practice and you should be able to do it without too many problems
General Custer isn't too bad a boss, The arrows are far worse a threat than his bodily excretions. You can easily one cycle him with the superscope before he gets across the screen to you. He's not particularly hard if you lose the superscope so don't fret if you fail first time round. The key differences in this difficulty is that custer moves and attacks faster, and that there are more arrows which move faster. The Bullshit man is the character to use for this as he does the most damage per second.
Overall the level doesn't have much changes but i found myself dying quite a few times, especially on the second breast section with the walls of death blocks.
Thy Farts Consumed - Difficulty 5/5. Rather fitting that the hell level is hellishly hard. There are a fair number of convenient skips but as i said earlier, the superscope is mandatory for this boss, if you don't have it you are really really unlikely to win.
After the spike pit and just before the cacodemon, instead of jumping over the fireball, switch to bullshit man, drop down and use your double jump to safely skip that portion of the level.
Use the glitch gremlin to make the section of dodging arrows considerably easier
Use mike to jump to the bossman area you'd normally farm lives for, and instead of climbing back up, drop down to the level below you, making sure to jump to the left as soon as you land to land on a block and avoid getting hit by the shark
Use the bullshit man from the block to knock out the shark making it safely ridable
Get the Superscope, and very carefully continue up the ladder, the two skulls that spawn below the platform can cause you serious grief as they like to stay out of reach from your bullets till it's too late
Watch out for the skull that spawns after traveling up the next ladder, as it once again spawns below the platform and can easily hit you and avoid your shots
There's yet another skull that spawns below the platform after the first set of arrows shot from the ceiling that you need to watch out for, and another one just after right before the wall of fire.
Be extremely careful when going down the ladder, there is a ghost/slime looking enemy right at the bottom, if you travel down too fast you can get hit and lose your superscope.
After that it's just tricky platforming, there is only one difficult part that you should practice of this which is
right at the end of it.
Grab the supermechadeathchrist3000
Deal with the skulls after climbing up the ladder, there are a couple that don't spawn untill the screen scrolls so take it slow here and it's then smooth sailing till you reach the boss.
The fun isn't over just yet though, just because you have the superscope doesn't mean you can walk over this boss, The pattern at first is very predictable, my advice is to hit it down to 2/3rds health then use the supermechadeathchrists to finish it off, If you die in this fight i highly recommend you restart, unlike the boss in Dungeons & Dickholes he moves too fast to be killable in a reasonable way.
Assholevania - Difficulty 1/5. This level is a cakewalk
Nothing much to say about this level. Using the superscope on Mr. Hyde makes him a doddle, even if you don't have the superscope at the end he's super easy to beat. (The ending part is pretty short and you can use the supermechadeathchrist 3000 to kill the enemies in the corridor)
For the large knights throwing axes at you, your best bet is to switch to bullshit man and fire projectiles at them from above to avoid unnecessary damage and deaths.
Happyfun Candytime - Difficulty 2/5. Very little challenge to this level in terms of enemies, just tight platforming (Which can easily be grinded out)
The only significant thing i can say is that the long spikes section towards the end of the level may prove to be a problem with only 2 beers making it much less lenient on what you can get away with. Luckily the Boss in this level is fairly easy
Use the supermechadeathchrist you find when climbing the waterfall on the section with loads of green flying enemies, you cannot reliably kill them all on time on this difficulty otherwise
Use mike to jump over the last spikes area before the bouncy green trampolines
For the boss fight nothing changes really, the fight just takes longer due to the weaker weapons (If you're good enough to have kept a superscope then this is a super quick bossfight) As with normal difficulty, stand on the top left platform and just shoot and dodge till you win. Rainbow Alicorn moves quite a bit faster than on normal difficulty when near half health but is still very easily dodgeable
Blizzard of Balls - Difficulty 4/5. The difficulty isn't really in the stage itself, for that i'd give it a 2/5 as the only real threats are the birds as they now poop in front of you making it easy to fall off ledges and die. But the boss for this stage alone bumps up the difficulty quite a bit. The boss for this stage is comparable to Fred Fuchs in terms of difficulty, the main advantage is that the ghost is a relatively quick kill.
As for the Ghost boss, the best strategy i could come up with is to stand in the middle and fire upwards, move to the left a bit just before they fire the spikes, wait for the ghost ghosts to separate out and circle, then jump up, move to the right of the platform, jump up again to avoid the second ghost and move back to the centre and fire upwards again, repeating the whole process until it dies.
The beer on the far right is barely accessible once the fight begins, and it's really easy to get hit by the spikes the boss throws at you when it's no longer vulnerable, combine that with how long it takes to kill the boss now and you're in for some fun...
Boo! Haunted House - Difficulty 3/5. This isn't much of a change from normal mode (Which in itself is pretty challenging), other than having to be much more careful when it comes to dodging the ghosts
The boss is incredibly easy on this stage, stand behind the death blocks at the far right of the screen and focus on killing Jason as quickly as you can, the timing for dodging him when he comes back on screen may take a few tried to work out but once you've got it it's super easy. Then just aim your gun up and kill the hand.
Laughin' Jokin' Numbnuts - Difficulty 5/5. As if i was going to say anything else about the difficulty of this level...
As this level is pretty much pure platforming there is no major change from playing in normal mode. The one key thing i noticed is that with 2 beers is that the sharks become a major threat in this level now. It's best to kill the two sharks, with guitar guy, before you need to jump to the platforms they can hit you from.
The Strategy for Fred Fuchs doesn't change from before (personally i like to keep to the left of the screen and jump between that and the middle to dodgy his spiky balls), he's just more resilient and you have less health in which to kill him with.
I spent just under an hour on this fight alone, it's certainly doable it just takes time.
I hope this is some help to anyone attempting this.