Details: One of the thirteen Special Trainers you will encounter at The Battle Tree after completing certain streaks with the multiple of ten in single player modes or team up with in multi-Battle mode is Colress, the former head of Team Plasma. He has seven possible Pokemon at the Battle Tree.
Possible Pokemon:
Muk (Air Ballon): Minimize, Acid Spray, Rest, Snarl
Muk (Liechi Berry): Cruch, Belch, Shadow Sneak, Stone Edge
Electrode (Air Balloon): Thunderbolt, Mirror Coat, Thief, Protect
Electrode (Damp Rock): Rain Dance, Thunder, Taunt, Light Screen
Porygon-2 (Eviolite): Tri Attack, Thunderbolt, Psychic, Ice Beam
Porygon-2 (Eviolite): Tri Attack, Thunder Wave, Shadow Ball, Ice Beam
Metagross (Occa Berry): Earthquake, Meteor Mash, Bullet Punch, Explosion
Metagross (Metagrossite): Zen Headbutt, Meteor Mash, Brick Break, Bullet Punch
Magnezone (Bright Powder): Charge Beam, Flash Cannon, Magnet Rise, Thunder Wave
Magnezone (Assault Vest): Thunderbolt, Flash Cannon, Tri Attack, Volt Switch
Porygon-Z (Expert Belt): Psychic, Ice Beam, Signal Beam, Charge Beam
Porygon-Z (Normalium Z): Tri Attack, Thunderbolt, Shadow Ball, Recover
Klinklang (Steelium Z): Shift Gear, Gear Grind, Volt Switch, Giga Impact
Klinklang (Leftovers): Flash Cannon, Thunderbolt, Protect, Toxic