1) You need to win
2) Outfit needs to be used in AoH, Sea Battle and in other places before full achievement is credited.

I used it in AoH, and I won a lot. You can ask dragonflylove and Nurse Ratched. However, I still did not receive credit for it

You need to win in ALL of those battlegrounds during 24 hour span not only AoH or Sea battles.

in 9-15 you dont need SB, only need to win aoh and 7b