Match Opening Strategy
Mega Man's best opening attacks are his jab (beats or trades with everything that is not armored) and his jumping LK, which comes out very quickly.
Best Assists
Generally his best assists are assists that help him control spacing or help chip: Doom rocks, Sentinel drones, or Blackheart anti-air. He also gains from Tron Bonne's Projectile (rings) assist, making him a dangerous assist-killer.
The Useless and Not Practical Rush Glitch
A practical joke video showing "Rush" was made by people from California. To get this, the other player's Venom does the web ball capture to Mega Man, walks forward and does another web ball capture just as his Magneto-A assist knocks you out of the first capture AND you Hyper Mega Man at the same time.
While the effects are cool (invulnerability, infinite HPs), this is obviously not a practical glitch.
MM Guides
Rockball trap
Jump back air buster, summon rockball, low kick rockball, release charged buster. Repeat. Add in an assist anywhere in the mix to keep opponents out.
Demonstration in a match:
