To me, Skylanders seem to be going down the 'nearly-all-animals' route in terms of what their characters are based on moreso than Pokémon. Sure, that series has got robots and spirits and such, but if you look at most of their guys, they're nearly all animal-like.
Now, dear old Pokémon, and the question of the hour; would it be better if they're all based on animals? No, not at all. Where else would we get such interesting chappys as the Regis? Or spooky 'mons like Golurk, Darkrai, and Dusknoir? I kinda like that Pokémon have diversified in recent years in terms of what things, creatures and concepts their 'mons are based on, and I'd like for them to keep that trend going.