I was thinking Choice Scarf too.
Ralts (M) @ Choice Scarf
EVs: 196 Spd / 236 SAtk / 52 HP
- Shadow Ball
- Hidden Power [Ice]
Psyshock is STAB and takes care of any specially defensive walls. Shadow Ball is coverage against mainly Ghost Types. Hidden Power Ice and Thunderbolt create a makeshift BoltBeam combo for more coverage.