Odigirb

hello. I new on the game, and i spend alot of time to undertand the IV and EV, and now i need help now... this game use Spatk and atk, for what kind of moves and pokemons its better? a few place says atk is for a contac moves and a few places say its for a atack type (Attack: Bug, Fighting, Flying, Ghost, Ground, Normal, Poison, Rock, Steel SpAtt: Dark, Dragon, Electric, Fire, Grass, Ice, Psychic, Water) so how its work here? ty for u time!