From Dragon Quest Wiki
Guerrilla is a skill introduced in Dragon Quest Monsters: Joker.
Dragon Quest Monsters: Joker
Guerrilla is learned by the Fencing fox, Mischievous mole, and Tyrantosaurus. It grants the following abilities:
Dragon Quest Monsters: Joker 2
Guerrilla is now also learned by the Robbin' huddle. Its abilities remain unchanged.