Each Pokemon has 508 useful EV's to spend and this is the MAX! it cannot go higher for any Pokemon. Secret Super Training does nothing but rewards you with special in-game items found here > Serebii.net
You can Ev train via Super training or Horde battling, Horde battling is far easier mind because with the right items/stats you could earn 60 attack ev's in 1 battle and probably max a Pokemons ev's in just under 15 minutes.
Wish you the best in future and goodluck!