You can't say that a couple is 'ultimate'
In terms of having over-the-top costumes? I think you can XD
Rasler and Ashe - Final Fantasy XIII
Abel and Esther - Trinity Blood
Watanuki and Yuko - xxxHolic
any Code Geass pairing with their artbook designs
Rosiel and Alexiel - Angel Sanctuary (relies on the "holy crap, awesome wings!" principle)