ocean's effect CAN be used to take back evil heroes.
quoted from yugioh.wikia.com:
"Elemental Hero Ocean" effect can be used on "Evil Heroes". The Japanese text mentions a 「ＨＥＲＯ」 monster, which to date includes "Elemental Heroes", "Destiny Heroes" and "Evil Heroes". "Evil Heroes" weren't mentioned in the English text, because they were not released at the time.