Shadow Pokemon arent massively different from their standard counterparts. They start at a fairly low level, their IVs are random, and their usual charge move is replaced with Frustration.
Once captured, players have the option to purify the Shadow Pokemon for a small Stardust and Candy investment. That instantly boosts the Pokemon to level 25 and increases each of their IVs by two. Frustration is replaced with Return, and the Pokemon in question can be powered up, evolved, and taught a second charge move at a slight discount.
