shadow force , 120 power + user disappars on first turn, attacks on second and hits through protect.
Giratina possibly. I don't know if Arceus counts when it is holding a Spooky Plate. But probably Giratina now.
shadow force
spirit tomb
A dark type Pokemon or a powerful dark type move is good. Ghost types work particularly well too
psychic lol i think
may be moltres
Serperior cannot learn any ghost type moves.
Mewtwo is weak against any bug type move, any dark type move and any ghost type move.
The most powerful normal type move is Giga Impact
The most powerful rock type move is either rock wrecker and head smash
It is a ghost type move.
Psystrike
The most powerful move is frenzy plant. Only the grass type starters of each region can learn it from a guy on route 228.
A dark type Pokemon or a powerful dark type move is good. Ghost types work particularly well too
Its eruption as the first powerful is blast burn.
Avalanche or Blizzard
psychic lol i think
may be moltres
A ghost type move.
With a ghost or dark type move.