Here is the full list of all 14 Critter Crunch achievements.
Win an online Versus match
Complete both Adventure mode and Puzzle mode
Complete 35 Adventure levels while also feeding Smalls to completion
Complete 25 Puzzle levels
Survive to level 9 in Survival mode
Unlock Survival mode
Complete 6 Combos in a single level
Pop a chain that is 15 critters long
Complete 10 Food Chains in a single level
Complete a puzzle level with moves remaining
Unlock Challenge mode
Unlock Puzzle mode
Complete Challenge mode
Reach experience level 5 in online Versus mode