As far as the Mega Man matchup is concerned, let's think about it this way.
Bringing up the menu is basically frame one. Accounting for the margin of error in human reaction times and canceling on a bad roll, Hero essentially gets 1 second of time to hope RNG works in his favor to bring out one attempt at Bounce, and that's merely for estimating how long it would take to retry a roll, and not accounting for the fact that ability to cancel/act out of the menu begins at around 20 frames, giving Hero a ~25 frame window at earliest where he's allowed to shield or spot-dodge if he's being aggro'd.
Nonetheless, one second is not an insignificant amount to pull out the move raw in neutral, assuming that's what Hero decides to do on instinct - and frankly I don't see there being a lot of moments necessitating Hero to pull out the move outside of advantage when Hero can already contest Mega Man's mid-range with Frizz and Zap. It doesn't take much for Hero to just hit someone off-stage. That's where he gets his opening - especially if he's already self-buffed with other commands like Acceleratle. Hero doesn't really need to worry about covering his coefficient in an unsafe situation unless he attempts to go for a desperation play. The moment the opponent is in any off-stage situation no matter how small, that's when he rolls the dice.
The raw numbers don't suggest that Mega Man is going to be able to out-camp Hero either. Despite Hero having a pretty mediocre aerial speed, his ground speed beats Mega Man's pretty handily (1.84 > 1.602), so realistically, Hero has ample opportunity to not only give himself room to pray to the RNGods, but also force aggression on Mega Man who possesses very few mid-range utility moves that aren't projectiles. Mega Man does possess air superiority, but I wouldn't hedge my bets on that against Hero's ability to trap landings.
Logistically speaking, Bounce should not be hard to dig out, and I don't think that's a discussion that needs to be had. However, that's not to say Mega Man is without options despite that. He still has a good set of aerials - something Hero kinda lacks - in the form of BAir and FAir. If Hero decides to not approach though, those moves aren't gonna be of much use. Everything Mega Man does that isn't a projectile is usually committal or low-range, with those aerials being an exception.
What I suspect Mega Man is really going to want to counterplay against Hero is his MP bar. Even though it's a tough proposition, finding an opening through his resources is going to heavily determine whether or not Mega Man is allowed to approach. I don't think it's unwinnable, but this is a match up that screams power creep.