What it does
Sap Sipper does two things: complete immunity to Grass-type moves, and a +1 Attack boost whenever a Grass-type move targets the holder (including friendly-fire in doubles).
The immunity alone has reach beyond just blocking Grass-type damage. Spore is a Grass-type move. So is Sleep Powder, Leech Seed, Stun Spore. A Sap Sipper holder walks into all of those completely unaffected — Spore's 100% accuracy sleep trap is simply switched off.
The Attack boost stacks every time a Grass move hits. In doubles, if the opponent uses a spread Grass move and it lands on your Sap Sipper Pokémon, you take zero damage and gain a free Attack stage. Stack it twice and you're at +2 without spending a turn.
One precision point: Attack boost only helps physical moves. Goodra runs mostly special attacks, so the +1 Attack rarely translates into damage. The value there is entirely the immunity.
Who runs it
Goodra: 67% Sap Sipper usage in Champions data — by far the most common carrier here. With 150 base Sp. Def, it's already a wall on the special side. Sap Sipper fills in the Grass immunity and ties off a defensive profile. The Attack boost barely matters on it; the whole point is coverage.
Azumarill: Normally runs Huge Power, which doubles its effective Attack and is almost always the better pick. Sap Sipper at 2% usage shows up as an alternative when teams need the Grass immunity more than the raw power. The trade-off is real — you're giving up doubled Attack for an immunity.
Drampa: Special attacker, so the Attack boost from Sap Sipper is cosmetic. Runs it at 2% mainly for the Spore immunity and Grass blocking in matchups where that stability matters.
Farigiraf and Wyrdeer barely appear in Champions data — not meaningful carriers.
How to use it
The clearest application: position your Sap Sipper holder as the Spore target when you see Amoonguss across from you. Amoonguss's Spore + Rage Powder combo is one of the premier doubles control tools, and Sap Sipper turns it off entirely. Your holder stands in front of it, Spore fails, and if you're running a physical attacker, you pick up a free +1 Attack in the process.
In doubles teambuilding, there's a niche pairing: have your own Pokémon use a Grass move that hits both your Sap Sipper holder and the opponent's side. You're attacking the opponent while giving your holder a free Attack boost on the same turn. Execution requires careful move selection, but it's a real line.
Goodra's use pattern: Thunder Wave or Dragon Tail for speed control and pivot utility, leaning on 150 Sp. Def to sponge hits while Sap Sipper seals the Grass and Spore angles. It doesn't need the Attack to go up; it just needs to not get slept.
Tips & strategy
The hidden Spore immunity is often more important than the Grass damage block. In Champions, Spore is the most accurate sleep option at 100%, and Rage Powder funnels it onto your key attacker. Teams built around Amoonguss lose a core tool the moment Sap Sipper is on the other side.
Don't expect the Attack boost to matter on special attackers: Goodra and Drampa deal damage through Sp. Atk. A +1 Attack stage doesn't change their damage output at all. If you're running Sap Sipper on a special attacker, sell it to your team as immunity, not as a damage boost.
Stacking against Grass-heavy teams: Against a team running Venusaur, Ferrothorn, or Amoonguss, every Grass move they use into your Sap Sipper holder charges up your physical output. Getting to +2 or +3 Attack off free Grass moves against a Grass-heavy team is a legitimate win condition if your holder can translate those boosts into damage.