I have some interesting points to say about ICs in doubles:
First, when you grab someone and start chaining them one of two things may happen. Their ally might be too far away or too busy to help and you are free to rack up insane damage and maybe even a kill... Or, their ally will start rushing towards you. When that happens you need to quickly put your grabbed opponent between you and the free opponent (Use an alternating backthrow for that), after that, you can either throw the grabbed opponent on the free one, or smash/blizzard them both when they are close enough. This is really effective.
Second, IC's are alot harder to seperate in brawl and Nana is harder to gimp. Any time your opponents spend chasing your seperated Nana is time you spend double teaming the other palyer with your ally.
Third, alot of moves in the game, mainly throws, can be used by your ally to get one opponent pretty high in the sky while you grab combo the other.
And about ChuDat... Sadly, we havn't seen him owning in brawl like he did in melee (Yet?!).