Greninja doesn't do anything better than the top/ high tiers, but overall he does more than them. Good recovery, good harassment and punish projectile, KO setups, disjointed forward air, good dash grab. Most top/ high tiers (excluding Sheik because that's just not fair) only have 1-2 of those. Although the only quickly noticeable thing he has over Sheik is KO power, so people who have never actually played Greninja for more than 10 minutes think he's just a bad Sheik.
Greninja not being as good as he deserves to be given his attributes has been a problem for a long time, though. He just doesn't work as well as he should; why are there enormous gaps between the percents that his down tilt combos (0-10%, then not until 80%-90%, then not until 130%)? Why does his up throw up air only combo sporadically, and not at all against some characters? Why is his extremely slow forward air not even a KO move from anywhere but the edge of the stage? That should be one of his defining features, a forward air that's slow but disjointed and can KO. Why does he still have a terrible standing grab, and the extra range really isn't worth the trade-off. The shuriken buff was big and showed an understanding of where he needed to start getting fixed, but he's still stuck at "good but not a threat."
