The brother of Freeza, Cooler desires to exact his revenge on those that killed his brother, in addition to taking the chance to eradicate all Saiyans from existence. Cooler eventually falls at the hand of Goku, but returns after a startling transformation into Meta Cooler. He watched Frieza destroy planet Vegeta. After Frieza was defeated he went to earth seeking revenge against Goku. Cooler like his brother can transform. Unlike his Brother Cooler can transform one step further. Unfortunetly for Cooler this wasn't enough to beat Goku and was thrown into the sun by Goku. In movie 6 he tried to take over planet Namek by merging with an alien ship. He fails of course and is killed by Goku this time for good.
Form 1 to 3 Although Cooler is never shown in any of his first three forms, we do know they exist. When he arrives on Earth and is talking with Goku he explains he is currently in his fourth form, and can even surpass it with a fifth.
Cooler - First form
Form 4 Unlike Frieza, Cooler prefers to stay in this form, and not use his 1st form when out of combat. Cooler is not only stronger than Frieza when in this form, but has much more control over it, and may explain why he could surpass it.
Cooler - Powered
Form 4 Full Power After Goku powers up and proves to be stronger than Cooler, Cooler decides to use what is thought to be his maximum level. Cooler's muscle mass and strength increases greatly, however he still proves no match for SSJ Goku. So thats why he goes one step beyond what his brother Frieza ever could.
Form 5 Although it is never exactly stated, it is assumed to be Cooler's ultimate form. He gets an enormous power-up and proves far stronger than Goku. That is, until Goku powers up. Once SSJ even the all powerful form 5 isn't good enough.
Cooler - Super Power
Meta Cooler After Cooler's previous defeat, parts of him lived on and actually become absorbed by a robotic star. The star then started producing millions of robotic type Meta Coolers. In this "upgraded" state he far surpassed his previous strength and in addition can have any mistake or flaw instantly fixed by the Big Ghetti Start when found. It is later shown that these are not the real Cooler, and are all being controlled by part of Coolers brain back in the Big Ghetti Star.
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