Normal Shot: Mega Buster: Pretty similar to his games, Mega Man can shoot up to 3 times for 2 damage each, as well as charge his shot for a medium and fully charged state, dealing 3 and 6 damage respectively, having to hold the NS button down.
Special 1: Steal Power: Upon neutral use, nothing happens. However, upon being closer to an opponent, Mega Man will copy their weapon, giving a brief moment of invincibility as well as gaining the ability of his opponents, similar to the games. The copied weapons costs the same amount of EP as its original, but also does +1DMG. He can also call Eddie using S1+Down to give him a random weapon from one of his main series, except the one your opponent "holds".
Special 2: Call Friends: Depending on the input, Mega Man will summon 1 of the 3 types of helpers during the match, but you've got to watch out, because your enemies can also utilize them. The default S2 summons Rush Coil, which quickly gives you a boost upwards if jumped on. S2+Up brings Rush Jet, giving you free air movement while riding him. S2+Down calls Eddie, for a HP or EP recovery! Eddie follows an item order, so try to remember what item he'll spill out next.
Extra: Mega Man has 2 "sub-classes" to choose on the character select screen, those being Mega2 and Mega 3, which bring their gameplay more to the OG games, with his movement and specials being limited to that specific game.
Mega Man is your typical "choose your game" type of character. He can either be really aggressive by charging his buster in combination with his weaponry, or play defensively and spam the basic buster shot while healing with Eddie, chipping away damage from opponents that are far.
At the beginning or end of a stock, calling Eddie for a weapon and HP/EP is a good option, since you'll have an advantage by holding 2 weapons or, if you die, gaining a weapon for free. Using R.Coil or R.Jet can also help stalling spawning opponents for their invincibility and dodge certain attacks.
Much like his gameplay in the classic games, Mega Man doesn't have too much options on melee range, since his shots usually extend into his buster, which makes him miss most of the times.
Missing his charged buster not only makes him vulnerable, but also invalidates the damage trades dealt with the time charging, specially against characters with reflects/deflects, since it'll be wasted quite easily.
Depending on the weapon given by Eddie, you can either quickly burn away your EP on few attacks or receive a "bad weapon" for the match-up.