Competitive Pokémon consists of exactly two phases. They are deeply coupled, and you can't understand one without the other.
Team Building: Choose and fully customize six Pokémon - species, moves, held items, stats, and tera types. The art side.
Battling: Use those six Pokémon to reduce all of your opponent's to zero. The science side.
flowchart LR
TB["🎨 Team Building<br/>(creative, iterative,<br/>open-ended)"]
B["⚔️ Battling<br/>(tactical, time-pressured,<br/>opponent-driven)"]
TB -->|"fields a team"| B
B -->|"win/loss reveals gaps"| TB
B -->|"metagame shifts"| TB
style TB fill:#003a70,color:#ffcb05,stroke:#ffcb05,stroke-width:2px
style B fill:#cc0000,color:#fff,stroke:#ffcb05,stroke-width:2px
Why we cover battling first
You need to know how to win battles to know which Pokémon are worth building.
Also: battling is hard. Team building is harder. We get there at the end.