Dash while firing your uncharged X-Buster to cause the shot to deal double damage. This is useful when you don't have time to wait for a shot to charge.
Some stages are a little different if you beat a certain boss first. If you beat Chill Penguin, the Lava in Flame Mammoth's stage will be frozen. If you beat Storm Eagle, the lights in Spark Mandrill's stage will flicker on and off. If you beat Launch Octopus, Sting Chameleon's stage will be partially flooded.
Must have Heart Tanks, Sub-Tanks, enemy weapons, and power-ups. Then, go to Armored Armadillo's level. Reach the final mine cart, which launches you through the air at the end of the level. Just before you reach the wall, jump up and climb the wall. At the top, there will be a large Energy Unit. Get it, and then jump into the pit and die. Repeat this step five times. On the fifth time through, a capsule will appear on that same ledge. Dr. Light will then give you a Ryu-style fireball for Mega Man to use.
Select the password option at the title screen and enter the following in the 3X4 grid, inputting the password from left to right, starting from the top left corner:
Password
Effect
8441 2176 4423
4 Sub-Tanks, All Turbo Hearts, All Upgrades, All Bosses Defeated
5724 8418 3588
All 4 Subtanks, no armor, no weapons, no hearts
2653 3858 7584
All 4 Tanks, all heart tanks, and all bosses defeated.
8447 4666 6156
All abilities, heart tanks, sub-tanks, all bosses defeated, Zero's buster
6624 5468 8588
All armor upgrades, subtanks
4723 2486 1324
All Bosses Defeated - No Leg/Body/Helmet/Buster/Heart/SubTank
4653 4688 7884
All bosses defeated 2 turbo hearts 2 subtanks
2137 3188 8121
All bosses except Boomer Kuwanger and Sting Chameleon dead.
2556 2582 7114
All bosses except Sting Chameleon dead.
3676 4667 5148
All powerups and armor upgrades, all bosses beaten the first time through.
3748 8612 5524
All Subtanks & Hearts, NO Armor & Weapons
6485 1146 2321
All Upgrades No bosses Defeated
5583 4618 5824
All Upgrades, All bosses defeated, 1 turbo heart.
4423 8832 7824
All Upgrades, Chill Penguin Defeated, Storm Eagle Defeated
8141 2136 4426
All weapons, sub tanks, hearts, and levels completed
4764 8768 7748
Arm Capsule only
5147 8437 4536
Armored Armadillo defeated
7374 2268 6281
Beat the top half, and have collected the power ups on the top half.
4764 5788 3748
Body Capsule only
5151 3427 4261
Boomer Kuwanger defeated
5286 7136 5124
Chill Penguin and Storm Eagle dead.
4768 7258 1871
Chill Penguin Defeated
5337 5377 4171
Chill Penguin, Storm Eagle, and Flame Mammoth dead.
2147 5277 1281
Chill Penguin, Storm Eagle, Flame Mammoth, and Spark Mandrill dead.
6431 5168 8171
Chill Penguin, Storm Eagle, Flame Mammoth, Spark Mandrill, and Armoured Armadillo dead plus slide ability and head capsule.
Get three sub-tanks and make sure one of your special weapons has less than full power. Then, with the weapon that has less than full power selected, grab a weapon capsule and immediately hit start. If you did it right, you'll have a fourth sub-tank. Fill it using the same method, just don't over fill or you'll delete it and your third one. It recovers health just like the a normal one.