Mega Man X3/Sub Tanks

Neon Tiger
The Sub Tank is almost in plain sight, at the top right corner of the large open area near the start of the stage. Use the dragonfly platform or vertical dash to get it.

Blizzard Buffalo
Get the Leg Upgrade later in the stage. Backtrack all the way back to the last ladder you climbed, climb up the wall, jump to the right, perform a vertical air dash, and stick to the left to get the Sub Tank. It is possible to reach the platform by simply dash jumping off the wall, however it is extremely difficult.

Tunnel Rhino
The Sub Tank is almost in plain sight. As you proceed the tunnel area, climb up the open ceiling on the right wall a little before the Bit/Byte room to get the Sub Tank.

Volt Catfish
Unlock Ride Armors. At the last area of the stage, climb up the far right wall, get on the Ride Armor Platform, select it, go back down to crash through the floor, proceed to the left, jump off the Ride Armor, and get the Sub Tank. Note that to make it there with the Frog Ride Armor, you will have to dash jump to get a high enough jump over a platform, although there is no real reason to use Frog over Chimera.