In Pokemon Masters EX, players can scout for Sync Pairs, which are character and Pokemon pairs that always go to battle together. The same character can be paired with a different Pokemon, but only after the game releases a different version of them. In that sense, you want to nurture the one Pokemon a trainer is bound to so that they can perform their best in battle.
While some Sync Pairs come with pre-evolved Pokemon, such as Signa Suit Red and Charizard, others come with pre-evolved forms, like Kris and Totodile.
To evolve Pokemon, start by heading to the Explore menu and selecting Sync Pair Stories. As its name suggests, you'll find all stories related to a specific Sync Pair you already own. If you see the Not Yet Evolved icon on the upper-right, the Sync Pair contains a Pokemon that you can evolve!
Related: How to get Elesa and Lisia Fan Tickets in Pokemon Masters EX
Select the Pokemon's Evolution Story to prompt a battle. It costs x5 Evolution Shard to initiate the battle for the first evolution. It costs x3 Evolution Crystal for the second evolution. If you lose the battle, you'll get your evolution materials back.
There's no level limit to evolving your Pokemon, so you can wait until you're ready—or choose not to evolve them at all. However, you'll miss out on stat and skill bonuses. But choose carefully, as once your Pokemon is evolved, there's no way to return them to their former state.
Check out our guide on How to increase Player Rank in Pokemon Masters EX to help you progress in the game!