Bowser is currently ranked 41st out of 41 characters on the official tier list, ranking himself as the worst character on the tier list, the same Melee placement ranking 26th out of 26 characters and a somewhat larger drop from his Brawl placement of 33rd out of 38.
In Project M, Bowser keeps most of his characteristics from Brawl and Melee. He is both the largest and heaviest character, but still has a somewhat high dash speed for his size, and his powerful attacks are offset somewhat by lag or awkward animations. His only recovery move, Whirling Fortress, maintains its strong horizontal capabilities while still being weak vertically. However, in Project M, Bowser's offense has been greatly buffed, giving him better damage, armor, additional shield damage, and less lag on many of his moves, making him excellent at dealing burst damage and, consequently, a terrifyingly dangerous force when he's in control of the match. Bowser's armor mechanic allows him to absorb the knockback and flinch effects from attacks of various strengths while performing certain moves, as well as during his dash, crouch, and crawl. As a result, Bowser can nullify what would otherwise be a potentially combo starting move, or simply plow straight through an attack intended to stop Bowser from advancing. Additionally, the damage buffs on his attacks now allow Bowser to outprioritize stronger attacks if his armored moves aren't appropriate. Even though he is a slower character, Bowser has high speed in some areas: besides his above-average dashing speed, Bowser Bomb can be cancelled before Bowser reaches its peak, allowing for quick follow-ups into the air that are impossible to achieve with his normal jumps.
The keystone of Bowser's combo potential is Koopa Klaw, which returns from Melee with some reworking. Instead of providing Bowser with a pummel, Koopa Klaw is now purely a grab, and now gives Bowser a down-throw option which spikes when used in the air while knocking grounded foes down, setting up a highly advantageous tech-chase. Bowser can use his down-smash or the quake hitbox on his up-smash to hit foes attempting to roll into him; the latter can keep foes close for another Koopa Klaw. Foes attempting to get up in place can easily be hit with a forward-smash, and its lingering hitbox and armor can easily circumvent the invincibility and weak hitboxes on get-up attacks. Meanwhile, foes who roll away from Bowser can be chased down thanks to his surprisingly high dash speed, which can outpace all but the quickest and farthest rolls. The versatility and numerous setups Bowser has off of this tech-chasing option, combined with his armor, shield-damaging capabilities, and highly damaging attacks, allow Bowser to easily dominate opponents who attempt to play defensively in close quarters with him. The forward- and back-throws off of Koopa Klaw, while nowhere near as useful as the down-throw, can set up an edgeguard when used from the ground, and at low percentages, lead well into all of his aerials. While Bowser's ordinary jump is often too slow to serve this purpose, using a cancelled Bowser Bomb can let Bowser quickly chase foes into the air at low heights.
Bowser has other setups at his disposal. Whirling Fortress remains a stellar out-of-shield option that can let him get the upper hand out of a defensive situation, and its first hit has lower knockback to keep damaged foes close enough for a combo. Fire Breath keeps its buffs from Brawl and remains a great tool for trapping foes too far away for melee attacks. It also now has a bite hitbox in its ending animation, punishing foes who attempt to DI close to him to punish the ending lag. Bowser Bomb is now a much safer move; in addition to its new cancelling capabilities, it is more damaging, it is armored (especially during its descent), and upon landing, it produces a shockwave that serves the same purpose as Fire Breath's bite, making the move harder to punish from the ground. The shockwave can lead into most aerials, an up-tilt, or a down- or up-smash.
However, Bowser's high gravity, large size (almost double that of his Brawl counterpart), and high weight make him susceptible to attacks and combos. Despite his speed in some aspects, he remains easy to out-maneuver, as he has relatively poor air speed. In addition, Bowser possesses one of the longest jump squats of the cast, leaving him with one of the slowest wavedashes in the game, though not the shortest. While it is difficult to send Bowser far due to his weight and moves with armor frames, it is fairly easy to send him off the bottom of a stage or gimp him, as he suffers from a predictable recovery that does not cover much vertical distance.
With his new buffs alongside his old weaknesses, Bowser is played best when used offensively enough to get in close range to opponents, but defensively enough to punish a foe instead of trying to start a combo himself. Bowser's new offensive tools can allow him to get KOs more easily than ever off of an opponent's mistakes, but his increased size and poor recovery necessitate that the player keep from making mistakes themselves.
Changes from Melee to PM
Likely as result of his poor competitive dominance in the previous games, Bowser has been heavily buffed in the transition to Project M. Many of his attacks are both quicker and more powerful. He has received widespread armor of varying levels depending on the move, and in addition some of his favorable traits from Melee such as the Koopa Klaw and Fortress Hogging return.
While his tournament viability is only moderate, his results are better than ever before.
Grabs and Throws
Giga Bowser remains Bowser's Final Smash in Project M. However, by holding a shield button at the character selection screen, it is possible for Bowser to start and participate as Giga Bowser permanently during the match, similar to how Zero Suit Samus was playable in Brawl. Starting from v3.0, Giga Bowser can now receive knockback in addition to damage, as well as now being vulnerable to status ailments like sleeping or getting buried, though his moveset has been improved to compensate for this, and he still cannot be grabbed. In 3.6, he gained the ability to pick up items and use the majority of them. Giga Bowser's main flaw is that he is extremely prone to combos because of his size and weight. His duration when summoned via Final Smash was also increased to almost twice as long. In addition to receiving most of Bowser's changes, some changes to Giga Bowser include:
Changes from PM to P+
FAF: First Actionable Frame
IASA: Interrupted as soon as
BKB: Base Knockback
KBG: Knockback Growth
(Taken from https://projectplusgame.com/changes/2.0)
v2.0 - v2.28
Up to date as of version 3.6.
In competitive play
Dry Bowser appears in Project M as Bowser's alternate costume. In the game New Super Mario Bros., Bowser falls to his apparent doom in a pit of lava, only to emerge and be fought later on in his skeletal form, Dry Bowser. He is an undead skeleton of Bowser (similar to how Dry Bones are apparent skeletons of Koopas) with an orange tuft of hair and his shell intact, though badly burnt. As of v3.5, Bowser's eyes gain an orange glow during certain attack animations as Dry Bowser. However, Bowser's moveset and sounds remain the same while playing as Dry Bowser.
Giga Bowser now additionally uses recolors correspondent to those of the regular Bowser, including a Giga Dry Bowser alt costume. Disregarding size, shell and tail, the latter costume looks exactly the same as the regular Dry Bowser, though with a more pronounced muzzle and additional spikes protruding from his chest and nose.
Project+ provides several new recolors for both Bowser's default and Dry Bowser costumes. Both Giga Bowser and Giga Dry Bowser are affected by the new color schemes. Additionally, Dry Bowser's attacks now use a blue fire effect instead of the regular red fire of his default costume. One of the new default palettes resembles his appearance on the Japanese cover for Super Mario Bros.
Z-Secret Costume: Dark Bowser (Mario & Luigi: Bowser's Inside Story).R-Secret Costume: Rookie (Mario & Luigi: Superstar Saga).
Z-Secret Costume: Giga Dark Bowser.R-Secret Costume: Giga Rookie.