Here is the full list of all 17 Mochi Mochi Boy achievements.
Clear a 5 floor dungeon
Clear a 10 floor dungeon
Clear a 15 floor dungeon
Clear a 20 floor dungeon
Clear a 25 floor dungeon
clear a 30 floor dungeon
Clear a 150 floor dungeon
Rescue every slime
Eat 50 monsters
Eat 100 monsters
Eat 200 monsters
Clear dungeon mode
Clear traps mode
Trigger a bomb
Touch a spike
Clear random mode
clear a total of 100 floors