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