SCARF DUGTRIO AS A CHECK
Dugtrio @ Choice Scarf
Ability: Arena Trap
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Earthquake
- Stone Edge
- Memento
- Pursuit/Toxic
Dugtrio normally cannot trap Tapu Koko due to Koko's access to U-Turn. It also normally cannot revenge Volcarona because at +1 Volcarona outspeeds and OHKOs assuming Rocks are up vs the Sash variant (Ground Z just dies). Greninja is yet another threat that could normally outspeed and take care of Duggy. With a scarf on, however, this is remedied. Koko no longer gets off freely vs Duggy:
252 Atk Dugtrio Earthquake vs. 0 HP / 0 Def Tapu Koko: 312-368 (111 - 130.9%) -- guaranteed OHKO
Those other threats I mentioned don't get off either. Volcarona is ofc OHKOed by SE, Greninja 2HKOed by EQ.
That being said, Dugtrio's bulk is the epitome of infamous. It cannot switch into any of Koko's attacks or it will die...right?
4 SpA Tapu Koko Hidden Power Ice vs. 0 HP / 0 SpD Dugtrio: 112-134 (53 - 63.5%) -- guaranteed 2HKO
That's right, folks. You read that correctly. If Koko is not carrying Brave Bird and does not predict that Duggy can, you know, actually switch in, and then go for U-Turn immediately, Dugtrio will come in and it will kill it. Brave Bird does OHKO though.
The set is standard - maximum speed and attack, EQ as the STAB, SE for Volcarona and general coverage, Memento for momentum and easing set-up, Pursuit for those pesky Latios and ghosts that think they can just switch out or Toxic to cripple a defensive mon.
tl;dr Scarf Dugtrio can switch in and freely defeat Koko; just watch out for Brave Bird, and it just wins.