Look below

(c) xdarkzerox
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SUB TANKS GUIDE
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1.	Flame Mammoth
	Requirments; Head upgrade, Leg upgrade
	Right after the heart piece go to the top
	of the side and go left top. Then keep going
	left till you go to the wall that is breakable.

2. 	Armored Armalillo
	Requirments; NONE
	After the first bot w/ instant death spikes, instead
	of being chased climb down and up real fast so you can 
	go where he was at. Or you can get chased and go to the 
	top part and let him pass by, and go back.

3.	Spark Mandrill
	Requirments; Boomerang
	Before going out of the first part of the level, head
	down to the sub tank that needs the boomerang to get.

4.	Storm Eagle
	Requirments; NONE
	After the first part of going up, head straight to the
	robot on the up/down platform that doesn't spit out fire.
	Destroy it and get on it up to the top, break the glass to
	get the ST.