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