Water:
Try Gyarados or, as I did (with another NDS) - Blastoise.
With fire, I had Infernape, but if you have no other Nintendo DS or friend/WiFi, you may try Houndoom, as user above me said. It could have Crunch, Nasty Plot and maybe Flamethrower or Dark Pulse, or maybe even Overheat.
I don't...