The Frontier Brains all have predetermined Pokémon and movesets, but the first Pokémon out is random. Natures, abilities, and genders are random.
Palmer
First battle (after 21 consecutive matches):
Milotic @ Shell Bell
- Surf
- Hypnosis
- Ice Beam
- Attract
Rhyperior @ Focus Band
- Earthquake
- Crunch
- Rock Wrecker
- Roar
Dragonite @ Lum Berry
- Dragon Claw
- Dragon Dance
- Aerial Ace
- Thunder Wave
Second battle (after 49 consecutive matches):
Regigigas @ Bright Powder
- Crush Grip
- Earthquake
- Stone Edge
- Drain Punch
Heatran @ Focus Sash
- Magma Storm
- Flash Cannon
- Earth Power
- Explosion
Cresselia @ Leftovers
- Psychic
- Signal Beam
- Ice Beam
- Moonlight
Dahlia
First battle (after 21 consecutive matches):
Dusknoir @ Iron Ball
- Shadow Punch
- Trick Room
- Will-o-Wisp
- Fling
Medicham @ Salac Berry
- Zen Headbutt
- Endure
- Reversal
- Fake Out
Ludicolo @ Muscle Band
- Waterfall
- Razor Leaf
- Drain Punch
- Swords Dance
Second battle (after 49 consecutive matches):
Zapdos @ Brightpowder
- Thunderbolt
- Air Cutter
- Heat Wave
- Signal Beam
Blaziken @ White Herb
- Flare Blitz
- Superpower
- Thunder Punch
- Night Slash
Togekiss @ Expert Belt
- Air Slash
- Aura Sphere
- Psychic
- Hyper Beam
Darach’s Pokémon have two movesets that he will use randomly. He will either have all of the first moves listed, or all of the second ones; they will not mix.
First battle (after 21 consecutive matches):
Staraptor @ King’s Rock
- Aerial Ace
- Double Team or Endure
- Return one Quick Attack
- Roost or Endeavor
Empoleon @ Razor Claw
- Waterfall or Aqua Jet
- Metal Claw or Drill Peck
- Brick Break or Rock Slide
- Knock Off or Shadow Claw
Houndoom @ Focus Sash
- Fire Fang
- Crunch or Thunder Fang
- Counter or Reversal
- Roar or Endure
Second battle (after 49 consecutive matches):
Entei @ Shuca Berry
- Fire Blast or Overheat
- Sunny Day or Shadow Ball
- Solarbeam or Extrasensory
- Hyper Beam or Calm Mind
Empoleon @ Quick Claw
- Earthquake
- Surf or Hydro Cannon
- Blizzard or Flash Cannon
- Signal Beam or Drill Peck
Gallade @ Scope Lens
- Psycho Cut
- Close Combat or Stone Edge
- Leaf Blade or X-Scissor
- Aerial Ace or Night Slash
Argenta will randomly use one of the Pokémon on this list
Thorton uses rental Pokémon from the same pool that you and your opponents use in the Battle Factory, although I could not find a list of these.
You didn’t ask for this, but here’s a list of every Pokémon the normal trainers can have, as well.
