It has been a long time since one of these threads existed.

Mega Decidueye
Grass/Ghost
Long Reach
HP: 78
Atk: 137 (+30)
Def: 75
SpA: 130 (+30)
SpD: 130 (+30)
Spe: 80 (+10)

Mega Incineroar
Fire/Dark
Intimidate
HP: 95
Atk: 150 (+35)
Def: 110 (+20)
SpA: 60 (-20)
SpD: 110 (+20)
Spe: 105 (+45)

Mega Primarina
Water/Fairy
Liquid Voice
HP: 80
Atk: 64 (-10)
Def: 88 (+14)
SpA: 150 (+24)
SpD: 150 (+34)
Spe: 98 (+38)