Well, the majority of Silvally's moves are physical, so Adamant or Jolly would be the more practical options, however the special moves it can learn offer quite the coverage. It has a few status options and utility moves (ie Swords Dance/Sub/Toxic), but not something that would build around. Since it can be any type, I would say take a look at an Arceus set that looks neat and try to match up with Silvally.