What it does
Steadfast raises the holder's Speed by one stage (+1) whenever it flinches — meaning whenever it loses its action during a turn due to a flinch effect from an attacking move. The Speed boost applies on the next turn.
The trigger is specific: the opposing move must have a flinch chance, and the flinch must actually proc. Flinch-capable moves in Champions include Rock Slide (30%), Air Slash (30%), Fake Out (100% on first turn out), and a handful of others. A regular hit that deals damage but carries no flinch chance never triggers Steadfast.
Who runs it
Lycanroc: 4% usage — most common Steadfast carrier here. 112 Speed, 115 Attack, Rock type. If it gets flinched by Rock Slide or Fake Out, the Speed boost lets it outrun targets it previously couldn't on the following turn.
Lucario: 3% usage. Steadfast is a secondary option — Justified or other abilities are more commonly chosen.
Gallade: 2% usage. 125 Attack, Psychic/Fighting. Speed boost after flinch can create new Speed tier opportunities, though trigger reliability is low.
Machamp: barely registers in Champions data.
How to use it
Fake Out is the only reliable trigger: Fake Out flinches 100% of the time on the first turn, making it the only fully predictable Steadfast trigger in the game. When the opponent uses Fake Out to skip your Pokémon's action, you come back with +1 Speed on the next turn. Whether that Speed shift matters depends on the current speed tier comparison.
Speed +1 stage in context: one stage is a ×1.5 multiplier. Lycanroc at 112 Speed jumps to ~168 after one boost — clearing a lot of unboosted mid-Speed Pokémon. If that converts 'slower than opponent' into 'faster than opponent', Steadfast just changed who moves first.
Tips & strategy
Flinch probability undermines reliability: Rock Slide flinches 30% of the time. That means more than two-thirds of Rock Slide hits on a Steadfast holder don't trigger the boost at all. Counting on Steadfast for consistent Speed gains doesn't work — treat it as an occasional bonus, not a core mechanic.
Steadfast vs. Inner Focus: Inner Focus prevents flinching entirely; Steadfast accepts the flinch and compensates with Speed. Not flinching in the first place is almost always better than flinching and gaining Speed — if you don't want to lose an action, Inner Focus is the direct solution.
Why it has low usage: Speed Boost provides +1 Speed per turn reliably; Swift Swim doubles Speed in rain unconditionally. Steadfast requires an opponent's specific move choice and a probability roll. The gap in reliability makes it a distant third option for Speed building.
Doubles flinch note: in doubles, Rock Slide can attempt to flinch both opposing Pokémon on the same turn. If both your Pokémon carry Steadfast, both can potentially gain Speed from one Rock Slide — but this is luck-dependent positioning, not reliable strategy.