Uh, some more ideas.
How about a Bonsai Pokemon?
Could be called Bonzizi...?
Ok this is an alright idea.
It starts out like two holly berries (Holiberi), one big one small.
Then it evolves into a little deer with the smaller berry at the end of it's tail. After this, it grows into a larger deer. (Oh yah, the horns are Holly Leaves) When this deer dies, the smaller tail grows into the larger berry of a new Holiberi! What do ya think?
Maybe a Pokemon representinng a Star? (No, Starmie does NOT count.)
How about a pokemon composed entirely of gems (Gemight?)
As for Poison/Flying type bird, that sounds great.
Maybe it feeds by letting other pokemon bite it, then they die from poison on the birds feathers. There's dinner for you!