How to Start the Sinnoh Gym Challenge and Unlock Double Battles

The Sinnoh Gym Challenge is the headline feature of this data pack, and it is the one that introduces double battles. You do not craft anything to begin it — you trigger it by defeating the prerequisite trainers that the pack places in your world.

Finding the entry point

Talk to the Radical Trainers NPCs that spawn around your world. The pack adds a chain of trainers whose defeat flags unlock the Sinnoh leaders. Work through the earlier, easier groups first; the unlock system gates the Sinnoh challenge behind them, so skipping ahead will leave the leaders unavailable.

Fighting the double battles

Once the Sinnoh leaders are unlocked, each gym encounter runs as a double battle rather than the standard singles format. Bring a team built for two-on-two: spread damage, Protect-style moves, and abilities that punish spread attacks all matter far more here than in a normal gym fight.

Beating the leaders

Every Sinnoh leader's team is built with maximum EVs and IVs, so you cannot out-stat them. You need type coverage, a speed plan, and answers to their aces. Expect the difficulty to sit in the medium-to-hard range, and expect to lose your first attempt or two while you learn each leader's lead Pokémon and switch patterns.