Mega Man X/Sub Tanks

Spark Mandrill Stage

 * Necessary Items: Boomerang Cutter

Proceed left from the start of the stage, using ladders to stay on the bottom level whenever possible. When you get to a dead end on the bottom level you will see the Sub Tank behind the wall. Use the Boomerang Cutter to grab it and the Boomerang will bring it back to you through the wall.

Storm Eagle Stage

 * Necessary Items: None

After your initial climb at the beginning of the stage, you'll find a turret sitting on a small platform. Destroy the turret and step on the platform. It will raise you up to a higher platform with a large glass window. Shoot the glass to gain access, then walk to the right and destroy the enemy you find there to shatter the rest of the glass. The Sub Tank is behind the enemy on the right.

Flame Mammoth Stage
In the large area with many platforms and lava on the ground (the lava will be frozen if you've beaten Chill Penguin's stage) climb up to the top platform and make your way to the left to find a 1-Up. If you dash jump to the left you can wall jump up the wall to see the Sub Tank behind two columns of breakable bricks. Break the bricks with your leg upgrade by wall jumping against them and the Sub Tank is yours.
 * Necessary Items: Leg Upgrade (Dash)

Armored Armadillo Stage

 * Necessary Items: None

Near the start of the level you'll be required to slide down a wall and will soon be followed by a reploid swinging a spiked bar behind you. Scroll far enough down the screen to start the reploid breaking through the wall, then wall jump back up. Drop behind it and move to the left to find the Sub Tank.