*sigh*
Why does everyone keep thinking those Pokemon isn't Pokemon-like? Digimon, Yu-Gi-Oh!, I don't understand...
Because, generally, Pokémon look more natural, being clearly based of animals and plantlife, whilst Yu-Gi-Oh monsters & Digimon are more abstract, occasionally being based of generic animals and plantlife, but having either mechnical or crystaline look added on to them too.
Also, generally, it's pretty clear what Pokémon are based upon, whilst Reshiram looks like a large, feathered bird with a dog's head, and Zekrom looks like an armoured... thing, with a giant drill for a tail. Hardly natural or animal.
Granted, Reshiram could probably be based upon large feathered/ dragon creatures of mythology, but Zekrom, especially due to it's armoured look, really looks like something you'd find in Digimon or Yu-Gi-Oh.
Dark Rainbow Dragon
Zekrom
MetalGreymon
Then again, as I said, when the ingame Sprites come out, I'm sure it'll have more of a Pokémon feel to it. And, all of this Yu-Gi-Oh/Digimon/Pokémon likenesses is purely subjective.