Here is the full list of all 31 Pummel Party achievements.
Skewer three players with the rocket skewer item
Hit three players with the remote control eggplant
Survive for 50 seconds in 'Bullet Barrage'
Start your first game
Place last in every minigame
Place first in every minigame
Knock off 5 players in one game of 'Snowy Spin'
Knockout 10 players in one game of 'Explosive Exchange'
Take no damage in 'Searing Spotlights' minigame
Control over 50% of the area in 'Elemental Escalation'
Win 'Magma & Mages' without taking damage
Complete 'Gift Grab' without collecting coal
As the lightning holder kill every other player in 'Thunderous Trench'
Got hit by the train in 'Temporal Trails'
Died in 'Acidic Atoll' throwing a barrel
Survive in 'Breaking Blocks' for 60 seconds
Collect 40 keys in 'Winter Maze'
Complete 'Rusty Racers' without falling off the track
Score over 5 in 'Bouncing Balls'
Survive for at least 50 seconds in 'Sorcerers Sprint'
Find the treasure in 'Sandy Search'
Get launched off screen in 'Tunneling Tanks'
Complete 'Slippery Sprint' without falling in the water
Win your first game
Get a double kill in 'Barn Brawl'
Accidentally blew yourself up in the 'Strategic Shockwave' minigame
Get a 5 player kill sreak in 'Speedy Sabers'
Steal the last gift in a players pile in 'Grifting Gifts'
Get your first goal
Win your first minigame