What it does
Chlorophyll multiplies the holder's Speed by 2 in sunny day or harsh sunlight conditions. This isn't +2 Speed stages — it's a direct multiplier applied on top of any stage modifications. The difference matters because stage boosts cap at ×4, but weather multipliers stack on top of that.
In practice: Venusaur at base 80 Speed runs around 121 Speed at Lv50 standard setup. Under harsh sun with Chlorophyll, that's ~242 — faster than essentially everything in Champions that isn't running its own Speed boosts. Near-guaranteed priority without using a priority move.
Chlorophyll only works in sun or harsh sun. Weather override instantly shuts it off — bring in a sand setter, rain setter, or snow setter and the Speed multiplier drops immediately. This is the defining weakness of sun teams.
Who runs it
Venusaur: 98% Chlorophyll usage, highest in this group and the canonical sun sweeper. Growth in sun boosts both Atk and Sp. Atk by 2 stages in one turn. Solar Beam fires without charging. Sludge Bomb provides Poison coverage. Chlorophyll's Speed doubles make sure Venusaur goes first after the Growth — one setup turn into a sweep is the whole plan.
Leafeon: 98% usage, physical slant at 110 base Attack. 95 base Speed becomes roughly 190 under sun. Solar Blade fires instantly. Hits harder per physical move than Venusaur but trades off coverage.
Scovillain: 69% usage. Grass/Fire typing means Fire-type moves get the sun weather boost (×1.5) on top of Chlorophyll Speed and Growth's doubled boost. Three sun-dependent bonuses stacked on one Pokémon.
Whimsicott: 1% Chlorophyll — almost always runs a different ability.
How to use it
Sun teams need a setter: a Pokémon with Drought or a Sunny Day user to establish harsh sunlight. Chlorophyll holders come in after sun is up. From there, the gameplan is fast offense under doubled Speed.
Venusaur's doubles pattern: sun setter establishes weather (or Drought activates on switch-in) → Venusaur uses Growth for +2/+2 → next turn, doubled Speed + boosted attacks + uncharged Solar Beam. Against teams without weather override, this sequence is difficult to stop.
Trick Room interaction: Trick Room reverses Speed order. Chlorophyll's doubled Speed becomes a liability — your Pokémon that's now 'fastest' goes last. Sun teams facing Trick Room need Taunt to prevent setup or a backup attacker that operates outside the Chlorophyll-Speed framework.
Tips & strategy
Weather denial is the core vulnerability: any opposing weather setter — Drizzle, Sand Stream, Snow Warning — overwrites harsh sun and cancels Chlorophyll. Sun teams need a plan to reestablish sun or to have non-Chlorophyll attackers that work in neutral weather.
Growth's doubling in sun: outside sun, Growth raises only Sp. Atk by +1. In sun, it raises both Atk and Sp. Atk by +2. That's a full two-stage boost to both offensive stats in one action. Chlorophyll Speed doubles ensure you're fast enough to take that action first.
Scovillain's stacked bonuses: Grass/Fire typing means Fire moves get weather ×1.5 in sun, Growth gives +2/+2 in sun, and Chlorophyll doubles Speed. Three sun-activated mechanics on one Pokémon. Breaking sun early against a Scovillain build is high priority.