It seems you can only ride specific Pokemon in restricted areas, so there likely won't be very many. Regardless, I'll be incredibly disappointed if we can't ride Rapidash. Lapras, Swasbuck and Arcanine would be cool too. And Bunnelby's evolution if it turns out to be a fairly large quadruped (which I'm expecting it to be).
Playing: Fire Emblem Awakening, Pokemon White 2, Bioshock Infinite I believe in everlasting life in Heaven.