Mega Man has always been an awkward character to play with, he does not have a lot of utility, and neither does he have impressive mobility. This is why he has been limited to stay in the lower section of the tier list; unfortunately, it is the case with the Mega Man in Smash Ultimate.
Nevertheless, if you love this cyborg, you can try him, because he still comes packed with his arsenal from the original Mega Man game, so that does add nostalgic value to him.
Super Smash Bros Ultimate Mega Man
Right of the bat, the most unique thing to notice about Mega Man is his Neutral Attack. He had the same Neutral Attack in Smash 4 as well, he shoots a fireball straight ahead, but now the fireball is a much more viable attack compared to the one he had in Smash 4.
This is mainly due to the increment in the travel distance of the fireball. In ultimate the fireball acts as a projectile, of course, it cannot fly off to the other end of the map, but it does have quite a decent range for a Neutral, this enhances his spacing game.
Speaking of his spacing, Mega Man has many tools to help him keep his enemies in check from a distance, because, like his Neutral Attack, he comes with many other projectiles. All of his special attacks are projectiles; he can throw a Metal Blade, fire a bomb, hit you with leaves and even throws his faithful dog at you. However, Mega Man does not excel at controlling space.
Do not get me wrong, Mega man is not a slow character, but the fact is that there are many characters faster than him. Mega Man will surely have a hard time creating space when facing such opponents. Mega Man himself has standard dash and walk speed, and he does not do any better in the air either.
In fact, he cannot maintain himself in the air, due to his lack of speed and because he falls faster towards the ground. His mobility has been slightly buffed in Ultimate, but I doubt that would make any significant impact on his gameplay.
Although he does not do well in the air, he did have a very powerful Back Air Attack. In Ultimate, his Back Air has been left as it is, but honestly, it is such a good move, that any further buffs might have made it broken. His Back Air has excellent range and a reliable hitbox, as well as a decent knockback and severe damage. Combined with the fact that you can potentially combo, off of it, makes it stand out even more.
However, in Smash 4, Back Air was the only move in the air, you could rely on, but that is not the case in Smash Ultimate. In Smash Ultimate, in order to match the dominance of Back Air, Forward Air has also received many significant buffs.
Previously in Smash 4, Forward Air was nothing to be thrilled about, it was in the shadow of Back Air, however now it has received all kinds of buffs. It has more range, activates faster, and has less ending lag and for the cherry on top, it now deals significantly more damage.
Now your aerial combat should commence with either a Back or a Forward Air attack. As for his grounded moves, his Down Smash is still uncontested, as the best kill move. However, due to the buffs received to his Up and Down Smash, they don’t seem like a bad option either, and can be used to mix things up a bit.
Overall, while the mega man has been gifted with better tools, that have more damage and range, he has been relieved of his jab locks and footstool locks; this will hurt him a lot since they were a crucial part of his arsenal. It is obvious that Mega man has changed, for better or worse, the same techniques are not applicable to him from Smash 4.