Since a neutral STAB is often better than a super-effective hit, you need useful resistances.
Dialga has the best defensive typing so far, Ghost/Steel would be pretty awesome too.
Dragon/Water is a very good mix of defensive and offensive types but the Dragon weakness puts it a bit lower than the Steel combos. Thankfully Palkia is fast enough to be able to destroy most other dragons before they can do anything though. --- Would you kindly read this signature?... PSN: SteveBob7 YouTube: SteveBob104