Hatterene

Hatterene has a small niche on full Trick Room teams as the most aggressive offensive Trick Room setter. Its very low Speed, Magic Bounce, and STAB Expanding Force let it dispel Amoonguss fairly easily, avoid some traditional Trick Room counterplay like Spore and take advantage of Trick Room itself to fire off powerful spread attacks under Psychic Terrain. Unfortunately, Hatterene's very low Speed, subpar bulk, and reliance on Psychic Terrain make it tough to use outside of dedicated Trick Room teams. Furthermore, it struggles against common Pokemon such as Rillaboom, Incineroar, Heatran, and Metagross. Indeedee-F is a mandatory partner to power up Expanding Force, block Fake Out, and help Hatterene set up Trick Room with Follow Me support. Amoonguss, Diancie, Porygon2, and Torkoal are other common Trick Room setters and beneficiaries that make for regular partners. However, most full Trick Room structures opt to forgo Hatterene for all-around better options such as Necrozma, leaving Hatterene as a niche option on an already niche type of team and therefore not particularly common or viable in Doubles OU.