General Techniques
Or at least the non-Rush ones
Music Cancel
Why Cancel the Music?
Mega Man 3's soundtrack, while amazing, generates lag. By removing the background music, the game simply runs faster.
Technique
By taking a spike death on the exact same frame as a screen transition, the "Mega Man dying" sound also causes the background music to stop.
This can be done in
- Doc Shadow (reliable)
- Dos Spark (50/50 or 75/25)
Other locations nobody goes for it
- End of Doc Gemini (no known setup, saves frames)
Other Music Cancel Locations
These use other one-off techniques of canceling music, at least partially for the same desired "no music = less lag" effect.
- Gemini Man - The Proto Man skip
Stop Hating Top Spin
Seriously. This weapon is much better than you think, it just has one major glitch that you can avoid once you know about it. It's actually quite powerful, just not as fast as other weapons in most situations for a speed run, mostly because at its core it's a melee weapon.
Avoiding Losing Top Spin on Shadow Man
Or, really, any boss with invincibility frames.
The problem is Top Spin triggers just about every frame it thinks it can hit an enemy. For Shadow Man, if he has invincibility frames, this means you get to watch the weapon ammo meter drain across 27 frames doing no damage.
The fix is very simple - just don't use Top Spin into invincibility frames. This goes for Shadow and Doc Heat.
Be Ready To Get Bumped Left
This is mostly noticed during the falling "Parishus" at the end of Shadow Man's stage.
Mega Man tends to get bumped left when killing an enemy with Top. Keep this in mind when trying to make tight jumps.
Boss Weaknesses
Weakness Order
Mega Man 3 has 2 weakness loops
- Magnet > Hard > Top > Shadow > Spark > Magnet
- Snake > Gemini > Needle > Snake
There are 2 soft weaknesses to "cross over" between the loops (at least 2 that are relevant to the speedrun routes), along with the two robots that take extra damage from buster.
- Spark takes 2 damage from Needle
- Gemini takes 2 damage from Shadow
- Magnet and Top both take 2 damage from the Buster instead of only 1.
Weak Against Theirselves
Most bosses are weak against their own weapon. Not as dramatically as our dear friend Metal Man, but enough that almost any robot's own weapon is a viable backup in refights. (Notably, Gemini Man's refight is routed to use Gemini Laser against him)