All Frieza needed to do is train to be super God like strong?

Then why wasn't cooler allot stronger than he was when he attacked them years before.

First off I love this movie its awesome but Frieza says that he became so strong because he never once trained before because he never needed to. Well when Cooler attacks them in DBZ he explains that he's allot stronger than Frieza because he's mastered his transformations allot better/faster than Frieza. Which means he must have been training. So I'm thinking that if Frieza became soo super strong soo fast just because he trained, why didn't Cooler become anywhere close to that power? Hes soo weak compaired to Frieza now.