Smash Ultimate · High Tier
Greninja has a lot of combos and a solid combo starter, so each of the moves doing that work becomes a little less effective at it.
Nerf around three moves per character that are too oppressive inside an already strong kit. Not every suggestion needs to be implemented.
Each entry lists the move or ability affected, the adjustment itself, and — where the analysis states one — the problem it is meant to solve and the reasoning behind it.
Greninja is one of Smash Ultimate's entries — the full tier-by-tier breakdown covers the whole roster.