Here is the full list of all 34 BOMBFEST achievements.
Unlock All Bombs and Stages
Unlock All Cosmetic Unlocks
KO 2 players with a single NON NUKE bomb
KO 3 players with a single NON NUKE bomb
KO everyone with a single bomb
Catch and throw away a slomo'd bomb
KO a player with a bomb they threw first
Self KO with the crown
Play a round with all bombs disabled and no timer
Steal first place from the wizard during the final round
Get saved from an explosion by the train in the Bedroom
Leap across the chasm on the Deck
Clear the stage of blocks in the Dining Room
Have a player inside each wooden house in the Garden
Land in the bowl found in the Living Room
Remove the entire tower from the Nook
Fall down the drain in the Kitchen
KO a player by pushing them into the toy car in the Toy Room
KO another player into the waste basket in the Study
KO a player through one of the outside walls in the Office
Survive when left with a single closed box in the Attic
Tilt the Big Duck to the side in the Bathroom
KO someone from across the stage with a thrown Ice Bomb
Stick 2 Sticky Bombs to a single player
Hit a single player 3 times with one Bouncy Bomb
Catch Bread and throw it back at the original thrower
Blast a player into a Button Mine's explosion
Get a KO with a Rocket volleyed at least 2 times
Catch a falling Nuke
Roll two 20s in a row on the Dicey Bomb
KO a player with a chain reaction involving at least 2 Potions Bombs
KO a player holding a Cotton Sword with a Cotton Sword