Regulation I is the standard ruleset for VGC 2025: no restricted legendaries, no Paradox forms. That kills Koraidon, Miraidon, Walking Wake, and Roaring Moon, but Iron Hands, Garchomp, and Incineroar are still legal — and still good.
1. Team composition: bring 4 of 6
Doubles is bring-4, which means you pick four leads + back during the 90s Team Preview. You almost never cover every threat — accept that you'll have a localized weakness and plan to play around it.
2. Terastallization
One Tera per match, one Pokemon per team. Think of it as a defensive retype OR a 2x STAB push, not just a +50% boost. Common uses:
- Tera Steel to wall Fairy moves (e.g. Iron Valiant Moonblast)
- Tera Fire to wall Garchomp's Earthquake
- Tera Fire on Pelipper to flip its Water weakness
3. Item diversity matters
Item Clause isn't enforced, but doubling up on Choice Specs means one counter shuts down two threats. Choice Specs + Life Orb usually beats two Specs.
4. Speed tiers
Doubles is slower than singles overall, but the speed tiers that matter (100 / 120 / 130 / 162 Arcanine) decide every Tailwind turn. Mis-tier your support and your Tailwind setup doesn't even get the jump on the opponent.
5. Clock
Official: 90s preview, 7 min total per side, 45 s per move. Plan, but don't overthink — trust your read in pool play and save the AI review for Top Cut prep.