Steadfastin Pokémon Polished Crystal

Steadfast is an ability that increases the Pokémon's Speed stat by one stage each time it flinches. This means that if a Pokémon with Steadfast is hit by a move that causes it to flinch, its Speed will increase, allowing it to potentially outspeed its opponent on the next turn. This ability can be particularly useful in battles where flinching moves are common, as it allows the Pokémon to gain a speed advantage over time.