Overdrive Ostrich - Crystal Hunter.
Wire Sponge - Sonic Slicer.
Wheel Gator - Strike Chain.
Bubble Crab - Spin Wheel.
Flame Stag - Bubble Splash.
Morph Moth - Speed Burner. (Magnet Mine charged up deals with the garbage)
Magna Centipede - Silk Shot.
Crystal Snail - Magnet Mine. Dash into his Shell to make him unable to enter it again.
Violen - Bubble Splash (Both Gathering Zero parts and at the X-Hunter Base)
Serges - Gravity Crush to get rid of his protection in one shot. Sonic Slicer and/or Magnet Mine.
Agile - Magnet Mine (both fights)
Zero - Speed Buner. YOU ONLY fight Zero if you DID NOT get all three of his parts. He'll deflect every single other attack, including Speed Burner, but with Speed Burner, get close so he cann't.
Sigma V 1 - Sonic Slicer.
Sigma V 2 - Strike Chain.
X-HUNTERS / GATHER ZERO
Violen - Bubble Splash.
Serges - Sonic Slicer &/or Speed Burner.
Agile - Magnet Mine.
*Shoryuken will work on most every boss.
By the time you face agile the second time you should have most if not all the powerups.
Now go in to the boss room and wait for agile to charge up his energy. When he has finished charging up, climb up the left hand side of the wall as quick as you can. Continue climbing until you are out of the screen.
Agile will setout a row of spikes and 4 sets of balls of light that go along the walls.
If you are out of the screen the balls of light will not harm you. Then all you need to do is slide down, Shoot and then climb back up.
Its possible to lose no energy this way.
Repeat this until all of his energy is gone.
If you have the X-buster powerup then you can give twice as much damage with it.
Get all of the heart tanks, sub-tanks, and armor upgrades.
In the third stage of the X-Hunters' base, you'll get to a fork in which there's a seemingly inaccessible ladder above and another ladder below you. Lure one of the bats to the ladders and use Crystal Hunter to turn it into a makeshift platform.
Climb up the ladder you can now jump to and keep going right until you see a winding passageway that's completely covered in spikes. You must use a charged Speed Burner (give yourself enough distance) in conjunction with an air-dash to clear this. Once you succeed, slide down the left wall with a full life gauge for a bit until you go through a fake section.
The upgrade you'll acquire from the capsule inside can defeat any boss (except for the last boss' second form) with one hit. To use it, quickly press forward, down, diagonal, forward (the same sequence you'd press to use an uppercut as Ken or Ryu in the Street Fighter games) and shoot. This move can only be performed at full health and can't be saved by a password.
Beat the game without getting any of Dr. Light's upgrades and Zero will show up when X is riding the bike in the ending.
Enter one of the following passwords to start at the corresponding game location.
Third X-hunter level
Enter 1462-3327-6482-3242 as a password.
All Bosses defeated
Enter 3467-8843-3528-7651 as a password.
First X-hunter stage after all Bosses defeated, all hearts, all energy tanks, all special capsules
Enter 8377-8143-6822-7651 as a password.
No levels completed, with all heart tanks, reserve tanks, and upgrades collected
Enter 4242-7183-1546-1681 as a password.
All power-ups and 3 Zero parts collected; all opponents except X-Hunters, defeated
Enter 3366-7123-6188-3681 as a password.
All sub tanks, hearts, and upgrades with only wire sponge left
Enter 2272-7123-1478-3446 as a password.
All Bosses defeated and all items
Enter 5462-3327-6488-3246 as a password.
Start with all of Zero's parts
Enter 7741-7732-3451-2748 as a password.
Note you will lose the items when you reach the Robot Screen due to a security reset on all passwords.