Pikachu315111, what type advantage does Turtwig have over Zapdos? Zapdos resists grass, and for Turtwig's line's eventual dual type, Zapdos takes no damage from ground at all.
And sure, Zapdos would undoubtedly be the best, if they were the only three pokémon in existance. But, in case you hadn't noticed, they're not. If you wanna draw up one of those charts like Pikachu315111's for all 493 Pokémon, and alternate form(e)s, go ahead.
In the mean time, Moltres is the best, because...Moltres!
Although in the anime, specifically the second movie, Articuno is of course much cooler (no pun intended...), it didn't go get itself captured now did it?