Location: Floccesy Town
Rebattle? No

Alder is battleable in Floccesy Town. When you visit after you have become Champion, Alder will state that he has heard of your skills and wishes to see them in battle. As such, he challenges you

Pokémon Trainer Alder	Accelgor	Escavalier	Bouffalant	Conkeldurr	Braviary	Volcarona
Battle Type Single Battle Items	Level 60	Level 60	Level 60	Level 60	Level 60	Level 62
	Sticky Hold	Shell Armor	Reckless	Guts	Keen Eye	Flame Body
	Attacks: Bug Buzz Focus Blast Giga Drain Acid Spray	Attacks: X-scissor Iron Head Reversal Swords Dance	Attacks: Head Charge Megahorn Earthquake Wild Charge	Attacks: Superpower Stone Edge Poison Jab Earthquake	Attacks: Crush Claw Superpower Aerial Ace Rock Slide	Attacks: Heat Wave Quiver Dance Silver Wind Psychic
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: Sitrus Berry

Location: Undella Town
Rebattle? Yes

Like in Black & White, Cynthia can be found in Undella Town during the Spring and the Summer. She will challenge you and will be able to be rebattled on a daily basis

Pokémon Trainer Cynthia	Spiritomb	Milotic	Togekiss	Lucario	Glaceon	Garchomp
Battle Type Single Battle Items	Level 76	Level 76	Level 76	Level 76	Level 76	Level 78
	Pressure	Marvel Scale	Serene Grace	Inner Focus	Snow Cloak	Sand Veil
	Attacks: Shadow Ball Double Team Dream Eater Hypnosis	Attacks: Blizzard Hydro Pump Attract Rest	Attacks: Extremespeed Aura Sphere Air Slash Thunder Wave	Attacks: Extremespeed Close Combat Flash Cannon Psychic	Attacks: Ice Beam Shadow Ball Signal Beam Barrier	Attacks: Dragon Rush Earthquake Stone Edge Fire Blast
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item
Spring/Summer Only

Location: Striaton Town
Rebattle? Yes

In Striaton City, the former Gym Leaders, Cilan, Chili and Cress, will each offer you to join them in battle against the other two. This battle is a standard MultiBattle and all the other trainers have three Pokémon. These battles can be done daily.

Pokémon Trainer Cilan	Maractus	Ferrothorn	Simisage
Battle Type Single Battle Items	Level 65	Level 65	Level 67
	Water Absorb	Iron Barbs	Gluttony
	Attacks: Petal Dance Sucker Punch Poison Jab Cotton Guard	Attacks: Power Whip Leech Seed Gyro Ball Curse	Attacks: Energy Ball Rock Slide Crunch Work Up
	Hold Item: Muscle Band	Hold Item: Leftovers	Hold Item: Life Orb

Pokémon Trainer Chili	Heatmor	Darmanitan	Simisear
Battle Type Single Battle Items	Level 65	Level 65	Level 67
	Flash Fire	Sheer Force	Gluttony
	Attacks: Fire Blast Sucker Punch Focus Blast Stockpile	Attacks: Flare Blitz Rock Slide Hammer Arm Bulk Up	Attacks: Flamethrower Grass Knot Crunch Work Up
	Hold Item: Leftovers	Hold Item: Muscle Band	Hold Item: Life Orb

Pokémon Trainer Cress	Basculin	Slowking	Simipour
Battle Type Single Battle Items	Level 65	Level 65	Level 67
	Reckless	Oblivious	Gluttony
	Attacks: Aqua Tail Double-edge Ice Beam Swagger	Attacks: Scald Psychic Flamethrower Calm Mind	Attacks: Scald Ice Beam Crunch Work Up
	Hold Item: Muscle Band	Hold Item: Leftovers	Hold Item: Life Orb

Location: Black City/White Forest
Rebattle? Yes

In Black City and White Forest, there are new battle areas known as the Black Tower or White Treehollow. These areas feature various trainers for you to defeat as you progress. At the end of the massive area, you will find Alder's grandson, Benga. His team varies based on which area you're in

Boss Trainer Benga	Latios	Garchomp	Volcarona
Battle Type Single Battle Items	Level 80	Level 80	Level 80
	Levitate	Sand Veil	Flame Body
	Attacks: Draco Meteor Psychic Icy Wind Thunderbolt	Attacks: Outrage Earthquake Fire Blast Stone Edge	Attacks: Fire Blast Bug Buzz Psychic Quiver Dance
	Hold Item: White Herb	Hold Item: Life Orb	Hold Item: Focus Sash

Boss Trainer Benga	Latias	Dragonite	Volcarona
Battle Type Single Battle Items	Level 80	Level 80	Level 80
	Levitate	Inner Focus	Flame Body
	Attacks: Draco Meteor Psychic Icy Wind Thunderbolt	Attacks: Outrage Focus Blast Fire Blast Dragon Dance	Attacks: Fire Blast Bug Buzz Psychic Quiver Dance
	Hold Item: White Herb	Hold Item: Life Orb	Hold Item: Focus Sash

Location: P2 Lab - Plasma Frigate
Rebattle? Yes

After you have defeated Team Plasma, their frigate will be docked at the P2 Lab and show that the people there are trying to reform. Colress is found on the bridge of this boat and will battle you. He can be rebattled on the deck of the frigate

Pokémon Trainer Colress	Magneton	Rotom	Metagross	Beheeyem	Magnezone	Klinklang
Battle Type Single Battle Items	Level 72	Level 72	Level 72	Level 72	Level 72	Level 74
	Sturdy	Levitate	Clear Body	Synchronize	Sturdy	Plus
	Attacks: Volt Switch Flash Cannon Tri Attack Thunder Wave	Attacks: Discharge Hydro Pump Will-o-wisp Substitute	Attacks: Meteor Mash Zen Headbutt Rock Slide Agility	Attacks: Psychic Energy Ball Calm Mind Recover	Attacks: Thunderbolt Flash Cannon Hyper Beam Thunder Wave	Attacks: Gear Grind Wild Charge Giga Impact Shift Gear
	Hold Item: Eviolite	Hold Item: Life Orb	Hold Item: Muscle Band	Hold Item: Leftovers	Hold Item: Wise Glasses	Hold Item: Air Balloon
P2 Lab Entry

Location: Nuvema Town
Rebattle? No
Memory Link Needed

If you have done the Memory Link feature, then as you enter Nuvema Town, Bianca will appear and state about how this was her first place of battle and where she set off on her journey, referencing the previous trainer. She will suggest battling you in memory of those times. She will use a team with Pokémon based on what she had in your version of Black & White

Pokémon Trainer Bianca	Stoutland	Chandelure	Musharna	Mienshao	Simisear	Samurott
Battle Type Single Battle Items	Level 63	Level 63	Level 63	Level 63	Level 63	Level 65
	Intimidate	Flash Fire	Forewarn	Inner Focus	Gluttony	Torrent
	Attacks: Ice Fang Surf Wild Charge Return	Attacks: Shadow Ball Psychic Overheat Return	Attacks: Yawn Dream Eater Psychic Return	Attacks: Drain Punch U-turn Fake Out Return	Attacks: Flamethrower Rock Slide Brick Break Return	Attacks: Aqua Tail X-scissor Aerial Ace Return
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item
If Snivy Chosen in BW

Pokémon Trainer Bianca	Stoutland	Chandelure	Musharna	Mienshao	Simipour	Serperior
Battle Type Single Battle Items	Level 63	Level 63	Level 63	Level 63	Level 63	Level 65
	Intimidate	Flash Fire	Forewarn	Inner Focus	Gluttony	Overgrow
	Attacks: Ice Fang Surf Wild Charge Return	Attacks: Shadow Ball Psychic Overheat Return	Attacks: Yawn Dream Eater Psychic Return	Attacks: Drain Punch U-turn Fake Out Return	Attacks: Surf Rock Slide Brick Break Return	Attacks: Leaf Storm Dragon Tail Coil Return
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item
If Tepig Chosen in BW

Pokémon Trainer Bianca	Stoutland	Chandelure	Musharna	Mienshao	Simisage	Emboar
Battle Type Single Battle Items	Level 63	Level 63	Level 63	Level 63	Level 63	Level 65
	Intimidate	Flash Fire	Forewarn	Inner Focus	Gluttony	Blaze
	Attacks: Ice Fang Surf Wild Charge Return	Attacks: Shadow Ball Psychic Overheat Return	Attacks: Yawn Dream Eater Psychic Return	Attacks: Drain Punch U-turn Fake Out Return	Attacks: Energy Ball Rock Slide Brick Break Return	Attacks: Flare Blitz Brick Break Wild Charge Return
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item
If Oshawott Chosen in BW

Location: Route 5
Rebattle? No
Memory Link Needed

If you have done the Memory Link feature, then as you enter Route 5, you will see Cheren his there. Reminiscing of his previous travels, he will challenge you to a battle, using his team from Black & White

Pokémon Trainer Cheren	Liepard	Unfezant	Haxorus	Gigalith	Simipour	Emboar
Battle Type Single Battle Items	Level 65	Level 65	Level 65	Level 65	Level 65	Level 67
	Unburden	Super Luck	Rivalry	Sturdy	Gluttony	Blaze
	Attacks: Fake Out Night Slash Shadow Claw Aerial Ace	Attacks: Air Slash Quick Attack Facade U-turn	Attacks: Outrage Rock Slide X-scissor Surf	Attacks: Stone Edge Stealth Rock Earthquake Giga Impact	Attacks: Surf Brick Break Payback Rock Slide	Attacks: Flare Blitz Head Smash Brick Break Wild Charge
	Hold Item: Sitrus Berry	Hold Item: Scope Lens	Hold Item: Dragon Gem	Hold Item: Leftovers	Hold Item: Mystic Water	Hold Item: Focus Sash
If Snivy Chosen in BW

Pokémon Trainer Cheren	Liepard	Unfezant	Haxorus	Gigalith	Simisage	Samurott
Battle Type Single Battle Items	Level 65	Level 65	Level 65	Level 65	Level 65	Level 67
	Unburden	Super Luck	Rivalry	Sturdy	Gluttony	Torrent
	Attacks: Fake Out Night Slash Shadow Claw Aerial Ace	Attacks: Air Slash Quick Attack Facade U-turn	Attacks: Outrage Rock Slide X-scissor Surf	Attacks: Stone Edge Stealth Rock Earthquake Giga Impact	Attacks: Energy Ball Brick Break Payback Rock Slide	Attacks: Hydro Pump Aqua Jet Blizzard X-scissor
	Hold Item: Sitrus Berry	Hold Item: Scope Lens	Hold Item: Dragon Gem	Hold Item: Leftovers	Hold Item: Miracle Seed	Hold Item: Focus Sash
If Tepig Chosen in BW

Pokémon Trainer Cheren	Liepard	Unfezant	Haxorus	Gigalith	Simisear	Serperior
Battle Type Single Battle Items	Level 65	Level 65	Level 65	Level 65	Level 65	Level 67
	Unburden	Super Luck	Rivalry	Sturdy	Gluttony	Overgrow
	Attacks: Fake Out Night Slash Shadow Claw Aerial Ace	Attacks: Air Slash Quick Attack Facade U-turn	Attacks: Outrage Rock Slide X-scissor Surf	Attacks: Stone Edge Stealth Rock Earthquake Giga Impact	Attacks: Flamethrower Brick Break Payback Rock Slide	Attacks: Leaf Storm Coil Dragon Tail Leaf Blade
	Hold Item: Sitrus Berry	Hold Item: Scope Lens	Hold Item: Dragon Gem	Hold Item: Leftovers	Hold Item: Charcoal	Hold Item: Focus Sash
If Oshawott Chosen in BW

Location: Icirrus City
Rebattle? Yes

After defeating the Elite Four, you will be able to encounter the Shadow Triad in Icirrus City. They will challenge you to a rebattle. These trainers can be rebattled once a season. One battle is a Single Battle, the next a Triple Battle and the final one a Rotation Battle

Team Plasma Shadow	Bisharp	Bisharp	Absol
Battle Type Single Battle Items	Level 65	Level 65	Level 67
	Defiant	Inner Focus	Super Luck
	Attacks: Night Slash Iron Head Low Sweep Scary Face	Attacks: Night Slash X-scissor Guillotine Swords Dance	Attacks: Sucker Punch Psycho Cut X-scissor Aerial Ace
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item

Team Plasma Shadow	Bisharp	Accelgor	Bisharp
Battle Type Triple Battle Items	Level 65	Level 67	Level 65
	Defiant	Hydration	Inner Focus
	Attacks: Night Slash Iron Head Low Sweep Scary Face	Attacks: Bug Buzz Giga Drain Focus Blast Sludge Bomb	Attacks: Night Slash X-scissor Guillotine Swords Dance
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item

Team Plasma Shadow	Banette	Bisharp	Bisharp
Battle Type Rotation Battle Items	Level 67	Level 65	Level 65
	Insomnia	Defiant	Inner Focus
	Attacks: Shadow Claw Sucker Punch Psychic Will-o-wisp	Attacks: Night Slash Iron Head Low Sweep Scary Face	Attacks: Night Slash X-scissor Guillotine Swords Dance
	Hold Item: No Item	Hold Item: No Item	Hold Item: No Item

Location: Castelia City
Rebattle? Yes

After defeating the game, you will be able to battle various people within GameFreak. These trainers have got solid, strong teams that can cause some serious damage and are among the highest levelled in the game. They can rebattled daily

GAME FREAK Nishino	Clefable	Wigglytuff	Azumarill	Alomomola	Lickilicky	Snorlax
Battle Type Single Battle Items	Level 76	Level 76	Level 76	Level 76	Level 76	Level 78
	Cute Charm	Cute Charm	Huge Power	Hydration	Own Tempo	Thick Fat
	Attacks: Cosmic Power Stored Power Metronome Sing	Attacks: Hyper Voice Thunderbolt Flamethrower Ice Beam	Attacks: Aqua Tail Double-edge Superpower Bulldoze	Attacks: Toxic Aqua Jet Protect Wish	Attacks: Power Whip Earthquake Fire Blast Blizzard	Attacks: Superpower Crunch Body Slam Yawn
	Hold Item: Leftovers	Hold Item: Leftovers	Hold Item: Leftovers	Hold Item: Leftovers	Hold Item: Leftovers	Hold Item: Leftovers

GAME FREAK Morimoto	Liepard	Simipour	Simisear	Simisage	Swoobat	Zebstrika
Battle Type Single Battle Items	Level 76	Level 76	Level 76	Level 76	Level 76	Level 78
	Limber	Gluttony	Gluttony	Gluttony	Unaware	Lightningrod
	Attacks: Sucker Punch Night Slash Fake Out Grass Knot	Attacks: Surf Payback Acrobatics Crunch	Attacks: Flamethrower Payback Acrobatics Crunch	Attacks: Energy Ball Payback Acrobatics Crunch	Attacks: Psychic Endeavor Air Slash Psyshock	Attacks: Wild Charge Pursuit Giga Impact Flame Charge
	Hold Item: No Item	Hold Item: Petaya Berry	Hold Item: Petaya Berry	Hold Item: Petaya Berry	Hold Item: No Item	Hold Item: No Item