Mega Man X2/Upgrades

Helmet Upgrade (radar)
Towards the middle of the level, after you defeat the mini-boss and slide down the slippery crystal slope, there is a big chasm. What you do is slide down the left wall of the chasm and there will be a path with some stationary enemies. Destroy them and keep going left until you find the capsule with the helmet upgrade (radar).
 * Stage: Crystal Snail
 * Items needed: none

This upgrade allows you to find hidden passages elsewhere in the game when equipped. When using the radar you cannot use your X-Buster or any other weapon.

Leg Upgrade (mid-air dash)

 * Stage: Overdrive Ostrich
 * Items needed: Spin Wheel

This upgrade is at the end of the stage before you enter the door to the rocket. Before you drop down to the door do a skip jump across the gap to a ledge that is blocked. You'll need to use the attack, spin wheel, to destroy the blocks blocking your way, inside is a small room with a capsule. Enter the capsule to gain the Leg Upgrade.

To use this upgrade jump then press the dash button to preform the mid-air dash.

X-Buster Upgrade

 * Stage: Wheel Gator
 * Items needed: none; Leg Upgrade recommended.

Towards the beginning of the stage after you go down the two ladders, and before you jump down the hole to the rocket platform, climb up the wall on the right. There will be a small overhang to the left and another longer overhang a short distance to the left of the smaller one, in the middle is a small hole. Make X grab a hold of the smaller over hang using mid-air dash. Then let Mega Man slide off the small over hang as soon as he lets go do another mid-air dash to grab the longer overhang. You can also do this without the Mid-Air Dash upgrade so you won't have to revisit here but it is very challenging to do, yet high rewarding in speedruns. After that climb to the top of the small hole and the capsule containing the X-buster upgrade should be on the right side of the room.

This upgrade allows X to charge up and shoot two powerful shots from both arms. Like in the previous game, it also allows X to charge all of the other special weapons he gains.

Body Upgrade (Giga Crush)

 * Stage: Morph Moth
 * Items needed: Spin Wheel

In the beginning of the level, after reaching the giant ceiling magnets, throw a few Spin Wheels onto the ground after the second orange column. There's no crack or anything, so be sure to throw it after the second orange column.

This body upgrade allows you to use the move Giga Crush, where after taking a certain amount of projectile damage (weapon energy bar must be full), X can unleash a powerful explosion attack that can deal massive damage to all enemies on screen. The attack doesn't work on bosses though. The upgrade also halves the amount of damage X takes as with the previous game.