I used to team with BlackWaltz quite regularly in the early stages of Brawl. As Olimar, he would camp EXTREMELY hard and take no risks. This resulted in him having a positive damage output, and let him get K.O.s easily. He threw pikman in as support, and could always whistle them back if he stuck me accidentally. He also was able to get easy kills by being opportunistic and Usmashing.
As Marth, I just mainly controlled the stage as I would with any partner, except I did not focus on landing kills, since I could just feed them to Olimar. This allowed me to remain safe enough to play a mostly 2 on 1 game the entire time.
Usually, everyone would be on their last stock high percent while Olimar was at 2 stock, low, pretty much assuring our victory.