http://en.wikipedia.org/wiki/Tonberry
Despite their small size and unassuming appearance, a Tonberry is a formidable opponent. They are tough and hard to kill. While a Tonberry's foes are attacking it, it will walk slowly towards them. Once the Tonberry has come close enough to its enemy, it will then attack with its knife; this attack is almost always fatal, landing the blow with a dull, anticlimactic "Doink."
Tonberries can occasionally utilize other attacks as well. In some games, after every successful attack that its opponent lands, it will counter with a very powerful special ability, such as that known as "Everyone's Grudge" or "Karma." This ability seems to call upon the departed spirits of every creature that the Tonberry's attacker has defeated in the past, and summon them forth for retribution.