Mega Man X2/Sub Tanks

Wire Sponge Stage
When you see a flying platform, step to the first one at very top and then dash jump to the left, then jump right to the next platform and you'll find the sub-tank here.

Flame Stag Stage
Wait for the first flying beetle to come, and aim the flying beetle to the very top and step on the top of their body (not head) and jump to the left and you'll get the sub-tank.

Magna Centipede Stage
Right before to the mini-boss room, there is a gap in the ceiling. Make sure when the multiple boxes fall to quickly pass over it, and then when another box falls, ride it and quickly dash jump to the right to get a sub-tank.

Bubble Crab Stage
In the open water area, charge up the bubble weapon and jump high. Then tap the jump key again to the left when in the surface.