Sonic is a playable character in the Brawl mod Project M. He has been buffed for his Project M showing. Sonic is currently ranked 10th out of 41 characters on the official tier list, near the top of A tier, and a considerable improvement over his placement in Brawl, where he was 22nd out of 38.
True to his series, Sonic is the fastest character in the game, having the fastest dash speed and a fast air speed. These traits make him able to rack up damage very easily and execute combos across the stage. His strengths include extremely fast and tricky movement, a great combo game, good edgeguards, and one of the best recoveries in the game. He has been given the option to moonwalk as a result of the game's return to Melee physics, which can help mix up his approach. He also now has the ability to dash jump, which almost doubles his already fast air speed. Sonic also sports a plethora of recovery options, as all four of his special moves can help him recover in some capacity.
While Sonic was known in Brawl for his high speed and movement, he was held back by his poor KO potential due to his extremely weak attacks and few finishers, all of which were unreliable and ineffective. This has been addressed in Project M, as he has been given more KO power in his moveset, making him stronger than before.
Sonic's flaws include having poor range on most of his moves (in addition to a lack of projectiles), poor hitbox placements, and weak horizontal and vertical endurance due to being light with only an average falling speed (even floatier characters like Samus take less vertical knockback due to her extra weight), while also being very susceptible to juggles despite generally not being easy to combo. As such, while Sonic can combo easily due to his maneuverability, he himself is very easy to K.O. at lower percents, as attacks with high power can send him flying off the stage for good despite his multitude of recovery options, and his low range and lack of projectiles compel him to come close to his opponents rather than heckle them from afar. As such, Sonic must make use of his speed and movement options in order to open up opponents and compensate for his weaknesses.
Changes from Brawl to PM
Sonic was buffed in transition to PM. His already impressive mobilty has been improved, he has more KO power and many of his moves have been altered to be more reliable and have more utility. While he has seen some nerfs mainly to his endurance and recovery, he overall has much better tools and the new mechanics of Project M benefit him more than they hinder him.
Grabs and Throws
Changes from PM to P+
Up to date as of version 3.6.
In competitive play
Sonic's colours have been changed to be significantly more obvious, improving his readbility in team battles. The non-default colours are all references to other Sonic characters, while his alternate costume is based on another series that was created by SEGA, Jet Set Radio.
In Project+, he also receives a set of recolors for his Jet Set Radio costume for Team Battles, while also receiving a new costume based on his Racing Suit from Sonic Adventure 2: Battle, while also receiving recolors for Team Battles.
Z-Secret Costume: Sonic Adventure design
R-Secret Costume: Werehog