What composition do you use on Team Islands in a team game?

I am mostly a land map player and not so experienced on water maps. So when I play team Islands in a team game I always wonder if it is better if one player goes for Galleons and the other for Fires (similar to land maps) or if just both players should go Galleons in castle age because they are stronger? And should both player open Fires in feudal age or should one go Galleys? And what do you do then in a 3v3 or 4v4?