Drain Punch for Gallade, SuperPower for Luxray.
Simple reasons, since your other Pokemon already (as you mentioned) have Close Combat, and sometimes, the extra HP is useful in-game.
As for Luxray, I for one, prefer Accuracy > other things, but then again, a lot of your Pokemon already have Fighting Type moves, so I guess trying out Iron Tail wouldn't hurt. Generally, though, given by the low PP of Close Combat, and the effectiveness of Fighting type moves in Platinum, I'd stick to Superpower.
