Piranha Plant (SSBU)/Up aerial
Piranha Plant strikes above with its head. Tied with forward aerial for its fastest aerial in terms of startup with faster endlag, autocancel and landing lag, making it a good move to purposely whiff to get reactions from opponents, as most of Piranha Plant's moves are relatively slow, thus making opponents think they can punish up aerial as well. It is also Piranha Plant's only move capable of autocancelling in a short hop, and it can also be fastfalled immediately to autocancel as well. One of the main uses of up aerial is when landing, as it provides the most diverse combos out of any of its moves, namely being able to lead to any aerial, up tilt, or Ptooie for extending combos further. It can also be used as an air-to-air with more reward over forward or neutral aerials, albeit at higher risk due to less range, despite the disjoint. If it lands however, it still has exceptional combo potential It is also good at juggling due to its speed, and when combined with Piranha Plant's fallspeed, it is easy to force landing options and punish quickly. The disjoint allows it to beat a number of landing options as well, making for a large threat when chasing opponents.
Up aerial is also a decent kill move from high up, and the frame 7 hitbox makes it difficult to react to, further helped by Piranha Plant's high jumps. It also can have minor use as an out-of-shield option, as it is tied with grab and forward aerial at frame 10 for its fastest OOS option. While it struggles hitting short characters, it can be used to hit opponents committing to constant pressure on shield with aerials. The move does possess glaring flaws however, notably in its hitbox. It is fairly small and only lasts 3 frames, giving it deceptively short front range and being difficult to use on standing opponents. This is mitigated by the fact that the move has head and stem intangibility, however, making it especially useful to beat opponents landing on top of Piranha Plant. A RAR up aerial is also good for anti-airing opponents not landing directly above Piranha Plant, especially as it is deceptively strong, useful for KOing.