Does training increase Pokemon stats? [duplicate]

Solution 1:

No.

The only way to increase the CP of a pokemon is to Power them Up using Candy and Stardust.

Battling a gym will either increase (if same team) or decrease (if other team) the prestige of the gym if you beat at least one of the pokemon stationed there.

Solution 2:

As Pokemon GO currently does not have EVs implemented (and CP seemingly doesn't change after training), training provides a Pokemon no advantage whatsoever.

However, training a Pokemon at a Gym will increase that Gym's prestige (and therefore level). The Prestige gains are dependent on how strong the Pokemon you're training with is compared to how strong the Gym itself is, in order to keep some semblance of balance in the game.