Start with a win condition
Choose the Pokémon you want to win games with — often a restricted attacker or a strong setup sweeper.
Add speed control
Every team needs a way to control speed: Tailwind, Trick Room, Icy Wind or priority. Pick the mode that suits your win condition.
Add support and disruption
Intimidate, redirection (Rage Powder / Follow Me) and Fake Out protect your win condition and buy turns.
Cover your weaknesses
Map your team's type weaknesses and make sure no single type sweeps you. Tera typing helps patch gaps.
Test and iterate
Use the team builder and matchup analyzer to find holes, then adjust. Team building is iterative and results are matchup dependent.