>>13386530T-tar and Empoleon/Skarm have good synergy with Sand Stream. Unfortunately, Steel is terrible offensively, so it kinda hinders your overall STAB potential. Still, it works. Your other three work good to counter Fighting-type attacks that might be thrown in T-tar's way. In fact, the only type that looks like it may give you any trouble is Electric, with only Giratina to resist super effective hits aimed at Emploeon and Skarm.
Really, it depends on what items/sets you'll be running, but from a type standpoint, you're pretty well off.
