Here is the full list of all 32 Bamerang achievements.
Throw 100 players off the platform
Throw 1250 boomerangs
Catch 5 boomerangs of your opponents
Land 500 hits
Play 10 matches
Throw 30 players off the platform
Play 10 unique maps
Pick up 1000 points
Hit three players at once
Land 100 hits
Throw 10 players off the platform
Hit two players at once
Throw 250 boomerangs
Hit each other at the same time
Catch a boomerang of your opponent
Hit a boomerang mid-air with your boomerang
Play 5 unique maps
Land 20 hits
Hit a player with a fully charged boomerang that flew a full curve
Throw 50 boomerangs
Play your first match
Throw someone off the platform
Pick up 100 points
Fall from the platform and get picked up by the goddess
Land the first hit
Throw the first boomerang
Play 50 matches
Play 100 matches
Pick up 10000 points
Catch 20 boomerangs of your opponents
Catch 99 boomerangs of your opponents
Play 25 unique maps