Purifying a Shadow Pokémon raises every IV by 2 and unlocks Mega Evolution, but you give up the Shadow attack bonus permanently — and Shadow Pokémon are some of the hardest species to re-acquire in Pokémon GO. The right answer is rarely "purify everything"; it is "keep it Shadow by default, and purify only when the right conditions overlap." This guide explains the three reasons to keep Shadow Pokémon in their Shadow form by default, and the three conditions where purifying actually makes sense.
The species this guide most often applies to (existing Shadow + Mega-eligible attackers):
Why You Generally Should Not Purify Shadow Pokémon
Three structural reasons make Shadow → purified the wrong default.
Reason 1: Purification Is Irreversible
Once you purify a Shadow Pokémon, you cannot turn it back into a Shadow form. The Shadow attack multiplier and the visual aura are gone for good. Lucky Pokémon, Hundo, costume — almost every other rare state in Pokémon GO is at least tradable or obtainable from another source. Shadow status is the only state in the game that you can permanently destroy with a single tap, so the bar to pull the trigger should be high.
Purified Pokémon do come with some perks — reduced power-up Stardust and Candy costs, a sparkle animation, and +2 to each IV — but combat-wise they function like regular Pokémon of the same species. Whatever raid value the Shadow form had is gone the moment you purify.
Reason 2: Shadow Pokémon Are Hard to Obtain and Cannot Be Traded
There are essentially only two ways to get a Shadow Pokémon:
- Team GO Rocket battles (Grunts, Leaders, Giovanni)
- Shadow Raids
A handful of large events (GO Fest, Tour, Special Research lines) occasionally hand out a specific Shadow as a research reward, but those are one-off encounters with locked IV floors. There is no walking buddy, no Wild Area pool, no field research RNG path that produces fresh Shadow IVs.
On top of that, Shadow Pokémon cannot be traded — not even as Lucky Trades. So if you purify a high-IV Shadow and regret it, you cannot ask a friend to send you a replacement; you have to grind Rocket battles or Shadow Raids again from scratch.
Reason 3: The Shadow Bonus Is Strong for Raid Attackers
Shadow Pokémon get a flat +20% attack (×1.2) and −17% defense (×0.83) compared to the same species' normal form. The actual in-game CP display does not change — the multipliers are applied at damage calculation — but if you re-compute the equivalent CP on attack and defense, the net effect is roughly a 10% virtual CP gain. The attack-side scaling is always applied during damage; the defense penalty matters only when you actually take a hit, which in raids is mostly during dodge windows.
For PvE raid metas, this puts Shadow versions of Dragonite, Tyranitar, Metagross, Salamence, Garchomp, and Mewtwo at or near the top of their respective type-DPS rankings. In raids, a high-IV Shadow you already worked for will usually outperform its normal counterpart as an attacker. Keeping it Shadow is the safer value-preserving choice.
(In Master League the picture is more complex because PvP also weighs bulk via SCP, so whether a Shadow is "stronger" depends on the matchup — but for PvE it is a straightforward upgrade.)
Bottom Line on the Three Reasons
- Irreversible — you cannot undo it.
- Hard to re-acquire — no trades, no Lucky Trades, only Rocket and Shadow Raids.
- Strong by design — Shadow attackers are top of the raid tier list.
Three structural one-way doors. The default has to be: do not purify.
3 Conditions When Purifying a Shadow Pokémon Makes Sense
That said, there are three specific situations where purification is not just defensible — it is the correct play. The more conditions are satisfied at once, the stronger the case for purifying becomes.
Condition 1: The Species Can Mega Evolve
Shadow Pokémon cannot Mega Evolve. If the species you want to use has a Mega form (and you actually plan to use that Mega for raids, Master League, or party power), then keeping it Shadow blocks one of the strongest power tiers in the game.
Many species already have both a released Shadow form and a Mega Evolution, including Tyranitar, Garchomp, Latios, Latias, 
Gardevoir, 
Pinsir, and the Kanto starters (
Venusaur, 
Charizard, 
Blastoise).
Important nuance: this condition alone is usually not enough. If your only Shadow Tyranitar has mediocre IVs and you also need a top-end Shadow raid attacker, purifying that single copy is a downgrade for raids while only marginally helping Mega usage (which lasts 8 hours per battle anyway). Combine this condition with Condition 2 or 3 below before pulling the trigger.
Condition 2: Purifying Lands You at 100% IV (15/15/15)
Purification adds +2 to every IV. So a 13/13/13-or-higher Shadow becomes a 15/15/15 (Hundo) the moment you purify it. If you care about Hundos for collection, PvP-CP optimization, or appraisal flex, this is one of the very few ways to create a Hundo on demand.
How does the Shadow + Purify route stack up against other Hundo paths?
- Wild catches: Hundo rate is roughly 1 in 4096 — pure gacha.
- Tier 5 raids: IV floor is 10/10/10, Hundo rate is about 1/216 ≈ 0.5%.
- Lucky Trade (Best Friend): IV floor is 12/12/12, Hundo rate is 1/64 ≈ 1.6%. See best Lucky Trade legendaries.
- Shadow Raid + Purify: IV floor is 6/6/6, and any roll of 13/13/13 or higher becomes a Hundo after purifying. That gives roughly 1/37 ≈ 2.7%.
So among repeatable raid-style routes, Shadow Raid + Purify is one of the most efficient ways to create a Hundo, at almost 6× the odds of a standard Tier 5 raid. If your Shadow Raid catch already shows 13/13/13 or higher, purifying it to lock in a 15/15/15 is a perfectly defensible call — but, again, only after Condition 3 has been considered too.
Calculation note: a Tier 5 raid has six possible IV values per stat (10–15), so the Hundo rate is 1 / 6³ = 1/216. A Shadow Raid catch has ten possible values per stat (6–15), and 13–15 in each stat purifies into 15/15/15, so the rate is 3³ / 10³ = 27/1000 ≈ 2.7%.
Condition 3: You Already Have a Second High-IV Shadow of the Same Species
This is the cleanest condition. If you already own two high-IV Shadow copies of the same species (or two that fill the same role), the cost of purifying one of them is small, because you still have a second one as your raid Shadow attacker. The first slot stays as Shadow for raids and Rocket; the second becomes a purified Hundo / Mega-ready / Trainer Battle copy.
- Copy 1 (keep Shadow): raid attacker, Rocket Leader counter, general PvE damage dealer
- Copy 2 (purify): Mega base, Hundo collection, possible Master League mirror utility
(Side note on Master League: some players have reported purified-copy behavior in true mirror situations, but standard CMP references treat identical Attack stats as random, and Shadow damage multipliers do not affect CMP. Treat this as a minor community-reported nuance, not a reason to purify by itself.)
Summary of the Three Conditions
- Condition 1: Species has a Mega form.
- Condition 2: Purifying produces a 100% IV (Hundo).
- Condition 3: You already have a second high-IV Shadow as backup.
If none apply: keep it Shadow. If two or more apply at the same time (e.g., a 13/13/14 Shadow Tyranitar + you already own one): purify is the right play.
Bottom Line
FAQ
Q. Should I purify Shadow Mewtwo?
By default, no. Shadow Mewtwo is the strongest non-Mega Psychic attacker in the game and is one of the highest-impact species you can keep Shadow. The exception is if your specific Mewtwo also has 13/13/13+ IVs and you already own a second high-IV Shadow Mewtwo to keep as the raid attacker — then purifying one for a Hundo / future Mega-Mewtwo run can make sense.
Q. Should I purify Shadow Tyranitar?
For raids, no — Shadow Tyranitar is one of the best Dark and Rock attackers in the game. The interesting case is Mega: a purified Tyranitar can Mega Evolve, and Mega Tyranitar boosts Rock raid output significantly. The clean answer is: keep your first high-IV Shadow Tyranitar as Shadow; purify only a second copy with 13/13/13+ IVs.
Q. Should I purify Shadow Latios or Shadow Latias?
Both species have a Mega form, so Condition 1 is satisfied — but that alone is rarely enough. For Shadow Latios as a Dragon raid attacker, keeping it Shadow is usually the better call. Purify only if the IVs are 13/13/13+ (Condition 2) or you have a second high-IV Shadow of the same species (Condition 3) so the Mega base does not cost you the raid attacker.
Q. Should I purify a Shadow Pokémon for Mega Evolution?
Mega availability alone is Condition 1, which we treat as "consider, not commit." Purifying a single Shadow purely for Mega means you trade a top-tier Shadow raid attacker for an 8-hours-per-battle Mega slot. Pair Condition 1 with Condition 2 (13/13/13+) or Condition 3 (second copy) before purifying for Mega.
Q. I caught a 13/13/13+ Shadow. Should I purify immediately?
Not on the spot. Going from 13/13/13 to 15/15/15 is great, but you are still trading a top-tier raid attacker for a Hundo display piece. Purify only if (a) the species also has a Mega you intend to use, or (b) you already own a backup Shadow of the same species. If neither, keep it Shadow — a top-IV Shadow is usually a stronger raid pick than a purified Hundo.
Related Resources
- Best Pokémon for Lucky Trade — Top 10 Legendaries — companion path to high-IV legendaries (Lucky Trade route to Hundos).
- Best Pokémon to Use Rare Candy On — once you've decided whether to purify, this guide tells you which species are worth your candy investment.
- Lucky Pokémon Guide — Stardust discount strategy that pairs well with the purification trade-offs above.
- All Pokémon Ratings — full per-species role grades, including Shadow / Mega availability per species.
About the Author
Doctor Pokégogo (about page) has been publishing data-driven Pokémon GO analyses since 2020. This guide combines Niantic's official Shadow / Purified Pokémon descriptions, current game-mechanics data for Shadow damage multipliers and purification IV changes, and Doctor Pokégogo's own raid DPS and PvP SCP datasets.