>>15671565But you're still stuck at base 100 stats unless you use up a turn to transform. 100 speed isn't slow, but it's still mediocre compared to other attackers. 100 spa/atk is decent, but nowhere near the power other attackers can muster and nowhere near the power to be a truly threatening attacker.
Compare with mewtwo, who has 154 special attack and 110 attack (why you would go physical, who knows, but it's better than mew in that regard) to completely fuck shit up. 130 speed is also outstanding, and it's only inferior by 10 points on def/sp.def compared to mew. It learns every meaningful coverage move, including boltbeam, flamethrower, and aura sphere (as well as the inaccurate stronger versions of each), an upgraded version of psyshock in psystrike (or psychic if that floats your boat), and hell even edgequake if you're crazy enough to go physical.
Protean mew would be a slightly better version of greninja due to coverage without stats a whole lot higher, or arguably even worse due to the speed difference.