Open the command console: ESC > Gear Icon > Under the keyboard tab select Advanced > Check off Enable Developer Console
Press the ` button to open the console and type:
map sd_doomsday_event; hostname "boost"; sv_lan 0; sv_cheats 0;
That will create your match. Choose the Red Team. Then type the following command:
mp_teams_unbalance_limit 0;
This will allow you to stack the opposite team. Then you can add as many bots as you like using the command:
tf_bot_add blue;
This can be done via any Bumper car game. I found that bumping them off the track wasnt the best way to go. The Spells seem to be the best way for the Soccer and Duck games. The other game with the disappearing floor is bet to hurry across and slightly tap every enemy before the floor beneath them gives away. For some reason knocking them off did not register but tapping them and letting them fall on their own did.