>Fire - dragon
>Water - Ninja
>Grass - ???
well, the ony thing that can catch up to dragons and ninjas popularity are pirates, vampires and... er, demons?
For pirate, making a grass starter half water is stupid. instead, make it a swashbucler grass/steel an acrobaic grass/flying (but not a bird) or a villanious grass/dark.
For vampire, dry skin as an ability perhaps? grass/dark is first thought, but also grass/ice (because cold as dead) or grass/ghost
Finally, demons.a devil grass pokemon, and again grass/dark comes to mind, or grass/psychic with plenty of tentacles and- no wait, that would kill the franchise.
(Yes, i know tengle)