Piranha Plant (SSBU)/Side special
Piranha Plant's head changes to that of a Putrid Piranha, shooting out a poison gas that moves slowly. Once it is onscreen, Piranha Plant cannot charge nor shoot another, and will instead shoot a slight amount of poison, with no hitbox, including the windbox typically present. The poison possesses no knockback whatsoever, in exchange for being able to cover a large amount of area and deal large amounts of damage, over 60% if the opponent stands in the sweetspot full charged. This makes the move exceptional as an area denial and ledgetrapping tool as a result. It also possesses a fairly weak windbox whilst shooting, however it severely lacks range and doesn't even have a rehit rate, unlike most other windboxes in the game, making it unusable in any realistic scenario.
As an area denial tool, its useful in forcing the opponent to play around the poison for the time it is out. Shielding the poison results in taking lots of shield damage, and when combined with neutral aerials or rapid jabs, can end up blockstringing into a shield break, in which Poison Breath can also be used as a shieldbreak punish to add enough damage for a forward smash to kill. Thus, opponents typically have to run through the poison and take damage, with the chance of getting hit whilst in it (grabs and rapid jabs are exceptional for keeping opponents within the poison and dealing extra damage), or have to jump above it, thus being prone to Piranha Plant's numerous powerful anti-airs. While it provides valuable use in neutral, and also helps in unstaling moves, the lack of knockback and high endlag can easily get Piranha Plant punished, especially with its head sticking out for a while, making it especially dangerous to use at close range, Thus, at close range, it is best relegated as a punish tool against very slow moves or reading a landing option with high landing lag, then grabbing or jabbing for more damage.
As a ledgetrapping tool, it does exceptionally well. Due to the hitbox of a fully charged Poison Breath, it can not only hit every ledgehang animation in the game, but also hit during two-frame animations and get guaranteed chip damage. It also forces the opponent to escape the poison from ledge, otherwise they take a large amount of damage. This, combined with usage of Ptooie rolls on the ledge, makes Piranha Plant's ledgetrapping incredibly strong with the proper reads on an opponent's ledge options. Important to note, is that an uncharged Poison Breath cannot hit every ledgehang in the game, so it is always best to charge the breath at least close to max, so it can hit ledgehanging opponents. It is also best to time a Poison Breath a bit before they grab ledge, in order to not get punished for doing it too late or have it not do much damage if any at all if done too early.
Against reflectors, Poison Breath can play a role against them. While Piranha Plant can end up taking massive amounts of damage from a reflected poison, it can be possible to exploit the lack of knockback in order to get a punish on the opponent reflecting. Grabs work best as the punish, due to being able to abuse throw invincibility to take less damage from the poison. However, getting caught by a reflected poison whilst performing a lengthy move can cause serious damage, so it is important to know when the opponent will commit to a reflector in order to punish them without taking extreme damage. Despite being an energy-based attack in the games code, it cannot be absorbed by the likes of PSI Magnet or Bucket.
The charge of Poison Breath also has uses in being able to be B-reversed and wavebounced, adding complexity to Piranha Plant's aerial movements and allowing for ways to fake out approaches against the opponent. The charge can also be shield or jump cancelled, with a light tap on the shield whilst on the ground causing a lagless cancel animation instead of going into shield. It is also possible to B-reverse the shooting of a fully charged Poison Breath, however it provides little to no benefit.
It also has very minor uses against certain characters in edgeguarding scenarios. It is able to destroy Villager and Isabelle's balloons on their up specials, and the lack of knockback prevents them getting out of free fall. Poison Breath can also destroy the trampoline on Pac-Man's up special, and Wario's bike as well. If Poison Breath is performed on a moving platform, it will move along the platform, and will stop at walls or have its direction altered by sloped floors, walls or ceilings.
This data is from charge release. Start-up animation is 10 frames.