Liitle Mac is the main character of the "Punch-Out" series. This series was very popular on the NES and SNES. It even got a revival for the Wii. Little Mac also appeared as an assist trophy in Brawl. He is a playable character in SSB4. Little Mac gets pink jacket from his trailer as an alternate costume.
Doc appeears in one of Little Mac's victory poses.
Most of his moveset involves punches, most commonly jabs and uppercuts. Many of these punches are very fast. His forward smash will animate and function differently depending on how it is angled; non-angled is a straight punch, up angled is an uppercut, and down angled is a body hook. Sakurai's Miiverse post about it implies the body hook deals the most damage, but also deals the least knockback. No information about the functionality of the other variations are known at this time.
Special Moves In Super Smash Bros. 4, special moves can be swapped out for different variants, but none of Little Mac's have been seen. These are Mac's special moves:
Neutral special move: Straight Lunge, a strong, chargeable punch attack. The move gives Little Mac launch resistance, and when released, Mac will charge forwards with a blazing punch.
Side special move: Jolt Haymaker; Little Mac lunges forward and a bit into the air, both avoiding attacks and closing in on the opponent.
Up special move: Rising Uppercut; "though it doesn't have a lot of jump power, it makes up for it with attack power". It has Little Mac spin repeatedly, similarly to Wario in the Corkscrew, which concludes with a skyward punch. This propels him upwards, but the move appears to give quite poor horizontal distance in comparison to other recovery moves.
Down special move: Slip Counter, when Little Mac uses Slip Counter, he will move his body backwards to dodge any attacks. The move will do nothing if Little Mac is not attacked, but if an opponent attempts to attack, a representation of a heartbeat will appear above Little Mac, and he will respond with a punch. This will nullify the opponent's attack, and cause damage and knockback to them.