Purifying is a trade. You hand back the Shadow Attack bonus, ×1.2, and get a Pokémon that's cheaper to raise and knows Return instead of Frustration. So it turns on whether you'll raid with it: 101 of the 515 Shadow attackers we rank reach Tier 4 or better.

What purifying changes

Scopely's help center says it will “improve their appraisal and reduce the amount of Stardust and Candy required for them to Power Up, Evolve, or learn a new attack.”

The Attack bonus goes back with it, and that's the part that decides this. The numbers behind it are on what a Shadow Pokémon is.

Keep these Shadow

The 12 hardest hitters of the 101, ranked against every attacker on the tier list, with the same Pokémon's damage once it's purified beside it.

Stardust doesn't buy that difference back. Ten more levels, 40 to 50, cost 250,000 Stardust and 296 XL Candy and raise Attack by 6.3%. The bonus is 20%.

And keep these, for what they become

A Shadow stays a Shadow through evolution. These 96 fall short of Tier 4 as they are, and every one of them turns into a Shadow that clears it.

Purify the rest

That leaves 282 of the 467 species that can be a Shadow. None of them reaches Tier 4, and none becomes something that does, so the Attack bonus buys you nothing and the surcharge on every power-up is real.

Powering one from level 20 to 40 costs 270,000 Stardust as a Shadow and 202,500 purified. That's 67,500 back, against a purification price that tops out at 20,000.

What the game charges

Two multipliers, and they're not the same number. A second charged move is discounted harder than a power-up: on the 50,000 Stardust price 204 Shadow species pay, that's 60,000 as a Shadow against 40,000 purified.

Evolving is priced per species instead. Scyther costs 50 Candy, and 45 once it's purified.

What purifying costs

Four Stardust prices cover everything, and every stage of a family pays the same one.

Frustration and Return

Every Shadow arrives knowing Frustration, and Scopely's help center gives one other way out: “Frustration cannot be unlearned with a TM until you’ve purified the Shadow Pokémon, except during special events.”

Purifying does it whenever you like, and hands over Return: “Unlike Frustration, Return can be unlearned at any time with use of a Charged TM.”

Ranks and damage come from the same model as the tier list: level 40, a perfect attack stat, against a neutral target. The multipliers, the purification prices and the power-up costs are read from the game's own data files.

Questions people ask

Should I purify my Shadow Pokémon?

Purify it unless you'll raid with it. The Shadow bonus is 20% more Attack, and 101 Shadow attackers reach Tier 4 or better on our tier list. The rest are worth more to you cheap, because purifying takes power-ups from ×1.2 to ×0.9.

Does purifying make a Pokémon weaker?

At attacking, yes. Purifying drops the ×1.2 on Attack, so a Shadow dealing 24.8 damage a second deals 20.7 purified. It also stops taking the extra damage a Shadow takes.

What does purifying cost in Pokémon GO?

Stardust and Candy, set per species: four Stardust prices from 1,000 to 20,000, and every stage of a family pays the same one.

Should I purify a Shadow before or after evolving it?

The price is the same either way, so nothing is saved by purifying early. What changes is what you give up, because a Shadow stays a Shadow through evolution. 96 Pokémon fall short of Tier 4 themselves and turn into a Shadow that doesn't, starting with Bagon.

Can I power a Purified Pokémon up to match a Shadow?

No. Ten more levels, 40 to 50, cost 250,000 Stardust and 296 XL Candy and raise Attack by 6.3%. The bonus you handed back is 20%.

Do Purified Pokémon do more damage to Shadow Pokémon?

No. The game's battle settings hold a Purified attack multiplier against Shadows, and it is set to ×1.0.

Can I get rid of Frustration without purifying?

Only at certain times. Scopely's help center: “Frustration cannot be unlearned with a TM until you’ve purified the Shadow Pokémon, except during special events.” The calendar tracks those events.

Is purifying worth the Stardust?

On anything you're going to raise, it pays for itself several times over. Powering one from level 20 to 40 costs 270,000 Stardust as a Shadow and 202,500 purified, a gap of 67,500 against a purification price that tops out at 20,000.