>>30147470If you're going for Null alone, Adamant might work because you're not gonna use Speed and Eviolite provides enough bulk.
If you're going Silvally, Adamant, Jolly, Modest, Timid... Any of them works. Adamant or Jolly allows you to use Multi-Attack, though. If you're going for Mixed, Lonely or Naughty allows it to focus on Physical, while Mild or Rash lets it focus on Special. Hasty and Naive makes it equal in offences, but it goes faster. Really, with Silvally, just pick what you want for it.