If your Pokemon has a good Basic move and you cannot figure out how it learns it, go to the Move Tutor in Pastoria City. Give him one Heart Scale for one move. Also, if your Pokemon accidentally forgot a move, you can do the same thing. The following is a list of good Basic Moves.

Abomasnow: Ice Punch
Charizard: Air Slash
Electivire: Fire Punch
Gallade: Leaf Blade
Garchomp: Fire Fang
Magmortar: Thunderpunch
Manectric: Fire Fang
Mew: Transform
Munchlax: Metronome
Octillery: Gunk Shot, Rock Blast
Piloswine: Ancientpower (how to evolve into Mamoswine)
Roserade: Weather Ball, Sweet Scent
Spiritomb: Shadow Sneak
Togekiss: Aura Sphere, Extremespeed, Air Slash, Sky attack
Torterra: Wood Hammer