What it does
Grass-type moves hit 20% harder. No HP cost, no lock. Non-Grass moves get nothing.
Who runs it
Leafeon at 32% is a physical Grass attacker with decent Speed, centering offense on Leaf Blade and Knock Off supplemented by Grass moves. After a Swords Dance, Miracle Seed amplifies the already-boosted output without Life Orb eating into the post-setup lifespan.
Serperior at 27% is the clearest case. Its entire offensive identity is Leaf Storm — Contrary flips the Special Attack drop into a Special Attack rise. Every Leaf Storm raises its power ceiling; Miracle Seed pushes each of those ceiling-raising hits further. Life Orb recoil would interfere with this snowball; Miracle Seed doesn't.
Tsareena at 12% uses Power Whip as its main damage tool — reliable physical Grass STAB that benefits straightforwardly. Venusaur at 7% uses it in non-sun builds where it's operating as a standalone Grass attacker rather than a weather team member.
How to use it
For Serperior: turn 1 Leaf Storm — Contrary raises Special Attack. Turn 2 Leaf Storm is stronger. By turn 3, accumulated Special Attack boosts may enable one-hit KOs on targets that survived earlier. Miracle Seed amplifies every step.
Only one Pokémon holds the item. If your team has multiple Grass attackers, give it to whichever most exclusively relies on Grass-type output.
Tips & strategy
Miracle Seed pairs interestingly with Giga Drain: the move recovers 50% of damage dealt. Higher base damage from Miracle Seed means higher absolute recovery — that extends the Pokémon's lifespan in a war of attrition.
Grass-type moves are naturally checked by Steel, Fire, Poison, and Flying types. Miracle Seed doesn't fix that type coverage gap. Against matchups Grass can actually handle, though, every hit lands harder.