What it does
Scrappy does one thing: the holder's Normal and Fighting moves can hit Ghost-type Pokémon, which are normally immune to both.
Ghost immunity to Normal and Fighting isn't a type resistance — it's a full nullification. Scrappy removes that immunity specifically for those two types. Ground moves still can't touch Ghost. Electric still can't. Only Normal and Fighting get through. And the damage calculation when they do hit is neutral (1× multiplier), not boosted — Scrappy just makes the hit land, not hit harder.
In practice: Kangaskhan's entire output plan is built around Normal STAB — high-power moves like Return or Double-Edge that hit everything for solid damage. A Ghost switch-in turns that plan off completely. Scrappy removes the wall. Return keeps connecting. Same logic applies to Fighting moves like Close Combat — they'd whiff against Ghost without Scrappy, but now they land.
Who runs it
Kangaskhan is the headline carrier at 98% — see it, assume Scrappy. Its whole identity is Normal STAB output, and Ghost immunity would be a crippling counter to that without this ability.
Pangoro at 92% is nearly as committed. It's Fighting/Dark, and its Fighting moves are the main damage source. Scrappy means an opponent can't freely bring in a Ghost to blank Close Combat and get a free turn.
Neither of these runs much else for good reason. Scrappy is too central to their function.
How to use it
The practical point: Ghost switch-ins stop being a free pivot against you.
Without Scrappy, a well-timed Gengar or Ceruledge swap turns your Normal or Fighting move into thin air and gives the opponent a free turn. With Scrappy, that same switch-in eats the hit. The opponent paid a tempo cost instead of getting a free ride.
In doubles this is particularly sharp — players will position a Ghost specifically as a blocker for Kangaskhan or Pangoro's Normal/Fighting moves. Scrappy invalidates the blocker entirely.
For Kangaskhan specifically: note that Scrappy is its ability before Mega Evolution. After Mega evolving, the ability becomes Parental Bond. The two forms serve different roles, but the base form's near-universal Scrappy rate signals the entire game plan — pure Normal STAB pressure.
Tips & strategy
Scrappy pairs best with high-power Normal moves — Return at 102 base power with Same Type Attack Bonus is the bread and butter. Without Scrappy, a Ghost swap turns that into nothing. With it, the damage just goes through at neutral.
Don't let Scrappy give false confidence. It only covers Normal and Fighting. Ghost types can still hit you with whatever they want, often at advantage — they commonly run Ghost or Dark moves that hit back hard. Know the matchup speed tiers and don't assume Scrappy makes Ghost types harmless, just un-immuneable.
Also: Scrappy is an innate ability, not transferable by moves like Skill Swap or anything that copies abilities into other mons in your team. The holder has to be on the field for it to matter.