Mega Man 3

On Controller 2, hold Up and A and most enemies will be frozen, making them easy to hit. Some enemies - for example, bosses - will not be affected.

Normally, to obtain the Rush Jet, you must get it by defeating Needle Man. Instead you can go to Shadow Man's stage and defeat him so that you acquire the Shadow Blade from him. Then, go to any other level and find a weapon energy refill capsule. Don't pick it up yet. Instead, open up the pause menu and highlight the Shadow Blades. Then press Right on the D-Pad, then press start to unpause the game and you should now have an empty weapon energy meter. Grab the weapon energy capsule and you will now fill up the empty energy meter. This energy meter is the Rush Jet. You can now summon the Rush Jet anytime.

In order for this trick to work, you must have Spark Shooter (SparkMan's weapon), but must not have defeated ShadowMan, the Robot Master who gives it to you. Go into the menu and point to Spark Shooter. While the cursor is on Spark Shooter, press right on the D-Pad. Rush's picture will appear instead of Spark Shooter's picture. Select this, and you will now have Rush Marine with an empty meter. Now, go pick up a weapon capsule or weapon pellet to fill the empty meter with. Once it has a little bit of energy, the Rush Marine option will now permanently appear on your weapons list, even when you deselect it.