I found this game quite easy... just the hit chance percentages are laaaame.
I beat bugzilla with, scientist, riot police, mochi hat, sledge hammer and grenade launcher. Used bug repellant, molotov cocktail, poison grenade, 2nd grenade launcher attack, (repeat when molotov effects cease). Stun grenade and heal when necessary. Final blow was a sledge hammer round the head. Win.