Kokuma, what you said reminds me of Pokemon Mystery Dungeon, where sometimes my Blastoise, Hinoqui, deals over 1000 damage though on the main screen it just says -999 in red numbers, instead of the usual white. In the message box, however, it says something like "Poochyena took 1027 damage!"
Same thing with me! While in usual Pokemon games(Diamond,etc) I always evolve my Pokemon, I didn't evolve myself or my partner in MD. It's hilarious... me(my character,Jenna the Chikorita) and my partner Mudkip would attack something like an Alakzam and do over 1000 damage with one attack(not a move). That's like a Chihuahua biting a tiger's toe and it dies.XD