What it does
Forest’s Curse is a Grass-type status move. On hit, the target gains Grass as an additional type alongside its existing types, lasting until it switches out. This means the target now has the full set of Grass-type weaknesses and resistances added to its existing type interactions.
Grass's weaknesses are Fire (×2), Flying (×2), Bug (×2), Poison (×2), and Ice (×2). Grass resists Water, Ground, and Rock (×0.5). Adding Grass to a target imports this whole interaction table onto them. A Pokémon that was previously neutral to Fire is now weak to it; one that resisted Ground before now finds that resistance potentially altered by the Grass interaction stacking.
This is a pure support move — no damage, one full action, the benefit arrives in future turns when teammates exploit the new weakness. The action economy cost is the reason this sees niche rather than broad use.
Note: Forest’s Curse cannot stack with Trick-or-Treat (which adds Ghost-typing). If the target already has an added type from either move, the new one overwrites it — only one additional type at a time.
Who runs it
Trevenant at 21% usage. Grass/Ghost-type, so it's using this move to create Grass weaknesses that it or a Grass-type teammate can follow up on. Natural Cure clears status conditions on switch-out, giving Trevenant some resilience when rotated out. Harvest triggers chance Berry recovery in sun, which pairs with Berry-dependent sets.
21% means this is a niche choice showing up in specific team concepts, not a format staple.
How to use it
In doubles, Forest’s Curse is worth considering when: a teammate has a strong Grass-type move and the target doesn't already resist Grass (or after the curse, gains an exploitable new weakness), and the setup turn is affordable given the game state.
The cost is one turn. If the game is at the point where winning requires immediate action rather than preparation, Forest’s Curse is the wrong call. It's a building tool — use it when you have a turn to spare and a teammate ready to exploit what follows.
One target per turn, one additional type maximum. Prioritize the target where a Grass weakness creates the most threatening follow-up combination.
Tips & strategy
The typing addition, not replacement — the target keeps all its original types and gains Grass. The full calculation applies across all three types simultaneously. Against a Fire/Water type for instance, adding Grass affects the type chart calc across all three, which can create complex interactions.
Opponents can negate the effect by switching the cursed Pokémon out — the added Grass-type doesn't persist across switch-outs. If the opponent anticipates the follow-up and switches, you've spent an action on setup that didn't pay off. In high-level doubles, this is the primary risk: savvy opponents rotate to remove the curse before the follow-up hits.