Apex Shadow Pokémon are stronger versions of Shadow Pokémon with unique and very powerful special moves. Like other Shadow Pokémon, Apex Shadow versions must be purified to increase their strength after being caught. Once Apex Shadow Pokémon are purified, they learn an even stronger version of their special attack.
Apex Shadow Pokémon are first introduced to Pokémon Go in the Johto Tour event as encounters for completing the Masterwork Research questline. The first Apex Shadow Pokémon in the game are Legendary Pokémon Lugia and Ho-Oh. These Pokémon appear with an intense purple aura and red eyes in their Apex Shadow form.
Once an Apex Shadow Pokémon is captured, players will have the option to "Purify" the Pokémon. Purifying costs Stardust and Candy, but will make the Pokémon much more powerful. Normal Shadow Pokémon develop a weaker charged attack, but Apex Shadow Pokémon get a huge upgrade to their charged attack when purified.
For example, Apex Shadow Lugia knows the Signature Attack Aeroblast+, but when purified, changes to Aeroblast++. These Signature attacks get a substantial boost when the Pokémon is purified so it is a good idea to try to purify them as soon as they are caught. The Apex Shadow Lugia and Ho-Oh are only available after completing the Johto Tour, which kicks off on Feb. 26.
For more Pokémon Go guides, check out Pokémon Go Grunts Guide: Lineup and Counters (February 2022) on Pro Game Guides.