Hold up plz, stop right there. With all due respect, I am honestly going to have to recommend against practicing MM when you're already playing like 6 characters. Yes, Mega Man is tough to use, his learning curve is high to very high and it takes tons of work and dedication to get good with him, easily among top 10 hardest imo and one of the weirdest characters to get used to. If you plan to get rid of 5/6 of those characters you mentioned and spend a lot of time playing Mega Man, then its worth it. Otherwise, its just not. Also, his damage output isn't that good, its quite weak actually. He's a low risk, low reward character who deals little to no damage in neutral and has mediocre combo setups, although his neutral is still fantastic nonetheless, among the top 10 best in the game probably.
Actually, unless you're a casual player who never plays in tournaments, I would try to cut down my character list anyway if I were you. When playing competitively, trying to learn multiple characters hurts you in the long term run and is likely to be severely detrimental to you, especially beyond locals. You can only practice one character at a time, and trying hard to learn your pocket characters can cut away time to practice with your actual main and leave yourself undercooked. Decent with many characters, master of none, and you're gonna have a hard time winning against those who are. Imo if you play seriously, I'd recommend 3 at most. Cause there's gonna be a looooooooooooooooooooooot of MUs to learn otherwise, and its not fun. If you're good, you don't even need anything more than a secondary and you can live without anymore, and if your character is good you don't even need any backup characters to begin with. Its your choice though, thought this would be something to keep in mind.