Mouser

Mouser is an evil humanoid mouse that works for Wart and lives in Subcon. His main weapon is the bombs that he tosses at his foes.

Mario & Luigi 3D
In Mario & Luigi 3D, Mouser invades Dinosaur Land working for Tatanga. Instead of his normal generic bombs, he uses Bob-Ombs, which are more dangerous. He is the first boss of the game. To defeat him the player must either jump on his head three times or use a Yoshi to eat the Bob-Ombs he tosses and spit them back out at him three times.