Mega Man X2/Heart Tanks

Overdrive Ostrich
Get Speed Burner, Leg Upgrade, and X-Buster Upgrade. Near the end of the stage, you see a Heart Tank sitting on spikes, Stand on where the spikes are (but don't touch it), charge up the Speed Burner, and then do the Air Dash, and get the Heart Tank. You will die after getting it.
 * Method one

After destroying the sand storm generator outside, backtrack until you find another hover-cycle and ride on to the next indoor stage. Ride over the spike section and retrieve the heart tank. If you time a turn properly, you will succeed in retrieving the heart tank without dying.
 * Method two

Wire Sponge
At the beginning of the stage, climb up the left wall.

Wheel Gator
You will see a Heart Tank, but you cannot climb up the wall due to the spikes.

Get Speed Burner, Leg Upgrade, and X-Buster Upgrade. Stand on the higher ledge, charge up the Speed Burner to the left, do the Air Dash, and get the Heart Tank.
 * Method one

Simply dash-jump and use the charged speed burner.
 * Method two

Bubble Crab
Get Bubble Splash, and X-Buster Upgrade. While you see the fish-looking submarine for the first time, charge up the Bubble Splash, stand on a orange rocket platform, do the dash jump, and get the Heart Tank.

Flame Stag
When you see a lava erupting, quickly destroy the enemy to get the Heart Tank (note that Spin Wheel can destroy most enemies in one hit, so use it here).

Morph Moth
Get Crystal Hunter. At the beginning of the level, freeze the disk-throwing enemy, use him as a platform, dash jump, climb up the wall, and get the Heart Tank.

Magna Centipede
Get Speed Burner, Leg Upgrade, and X-Buster Upgrade. Avoid touching the yellow lights. Stand on the ground between the turret, and the giant blocks, facing left, charge up the Speed Burner, do the Air Dash, and climb up the ceiling gap, and get the Heart Tank. If you got caught by the lights, go ahead to the right a bit and go back, the turret won't fall down and shoot you.

Crystal Snail
Get on the Robot Walker, head left back up the ramp, fall in the gap, go to the left, do the dash jump, jump off the Robot Walker, shoot S. Chain, and get the Heart Tank. You can also more safely get the heart tank by dash-jumping, hover with the Robot Walker, jump off the mech and use Giga Crush which slightly move you a bit that will help you from the pit. You can return to the other side of the pit without either S. Chain or Giga Crush.