A few times during the game your rival will challenge you to a battle. Usually appearing in key story locations, his team will always be a few levels higher than most other trainers in the area, on par with what you'd expect on the next route over. His team is quite balanced so approach him with caution; however, by the second or third fight it predictably turns into the same few Pokemon (including an elemental trio) and their respective evolutions.

The final evolution of Eevee he takes depends on the first few battles you have with him. He'll get Jolteon if you beat him in the lab and on Route 22, Flareon if you win the battle at the lab only, and Vaporeon if you lose the battle at the lab and the one on Route 22 or pass it up.

Encounter #1 - Oak's Laboratory

Location: Pallet Town

Details:
The first fight takes place right after being robbed of your starter. Your rival will steal Eevee while Oak gives you Pikachu; however, since the only attacks either of you have at the beginning belong to the Normal-type, you have nothing to fear, except the same type attack boost Eevee gets. It should be an easy first match as long as he doesn't score a critical hit.

Rival Eevee
Battle Type
Single Battle
Items
Level 5
Attacks:
Tackle
Tail Whip

Encounter #2 - Route 22

Location: Route 22

Details:
Left of Viridian City your rival will be training his starter and newly caught Spearow; this remains applicable until you pick up your first badge. Though the first should be easy enough with your starter, you may want to grab a Mankey in the nearby grass if Eevee gives you trouble.

Rival Spearow Eevee
Battle Type
Single Battle
Items
Level 9 Level 8
Attacks:
Peck
Growl
Leer
Attacks:
Tackle
Growl
Sand-Attack
Encounter #3 - Nugget Bridge

Location: Cerulean City

Details:
On the way to the Sea Cottage on Route 25, your Rival will be waiting on Nugget Bridge for your challenge. Rather than helping Bill change back from being a Pokemon, your rival decides hanging out on the bridge is better use of his time. His team has expanded to include a Rattata and Sandshrew. As his starter will still be in its basic stage the most you'll have to worry about is Sandshrew's Sand Attack blinding your Pokemon and Rattata's Hyper Fang inflicting massive damage. Eevee is still pretty weak so deal with it with something weaker that you need to train.

Rival Spearow Rattata Sandshrew Eevee
Battle Type
Single Battle
Items
Level 18 Level 15 Level 15 Level 17
Attacks:
Peck
Growl
Leer
Fury Attack
Attacks:
Tackle
Tail Whip
Quick Attack
Hyper Fang
Attacks:
Scratch
Sand-Attack

Attacks:
Tackle
Growl
Sand-Attack
Encounter #4 - S.S. Anne

Location: S.S. Anne

Details:
Kind of like the last time you fought him, only things are at a higher level. Sandshrew has Slash now, which has a higher critical hit ratio. This fight shouldn't be any harder than the last one because it's pretty much the same team.

Rival Spearow Rattata Sandshrew Eevee
Battle Type
Single Battle
Items
Level 19 Level 16 Level 18 Level 20
Attacks:
Peck
Growl
Leer
Fury Attack
Attacks:
Tackle
Tail Whip
Quick Attack
Hyper Fang
Attacks:
Scratch
Sand-Attack
Slash
Attacks:
Tackle
Tail Whip
Sand-Attack
Growl
Encounter #5 - Pokémon Tower

Location: Lavender Town

Details:
This is where rival's team really takes shape. By now his Ratatta has left the party (strange considering he speaks of dying Pokemon and is hanging around infront of a grave...) and been replaced with the second and third of the elemental trio he'll have in coming battles. Your team should be reasonably balanced and ready to handle the newly evolved Fearow like last time as well as his two newcomers. Fortunately his movepools leave much to be desired still so use that to your advantage. If your rival is using a Shellder avoid using physical attacks as they'll do nothing with the Pokemon's obscene Defense.

Rival Fearow Sandshrew Vulpix Magnemite Eevee
Battle Type
Single Battle
Items
Level 25 Level 20 Level 23 Level 22 Level 25
Attacks:
Mirror Move
Growl
Leer
Fury Attack
Attacks:
Scratch
Sand-Attack
Slash
Attacks:
Ember
Tail Whip
Quick Attack
Roar
Attacks:
Tackle
Sonicboom

Attacks:
Quick Attack
Tail Whip
Sand-Attack
Growl
Evolve Into Vaporeon
Rival Fearow Sandshrew Shellder Vulpix Eevee
Battle Type
Single Battle
Items
Level 25 Level 20 Level 23 Level 22 Level 25
Attacks:
Mirror Move
Growl
Leer
Fury Attack
Attacks:
Scratch
Sand-Attack
Slash
Attacks:
Tackle
Withdraw
Supersonic
Clamp
Attacks:
Ember
Tail Whip
Quick Attack
Roar
Attacks:
Quick Attack
Tail Whip
Sand-Attack
Growl
Evolve Into Jolteon
Rival Fearow Sandshrew Magnemite Shellder Eevee
Battle Type
Single Battle
Items
Level 25 Level 20 Level 23 Level 22 Level 25
Attacks:
Mirror Move
Growl
Leer
Fury Attack
Attacks:
Scratch
Sand-Attack
Slash
Attacks:
Tackle
Sonicboom

Attacks:
Tackle
Withdraw
Supersonic
Clamp
Attacks:
Quick Attack
Tail Whip
Sand-Attack
Growl
Evolve Into Flareon
Encounter #6 - Silph Co

Location: Silph Co.

Details:
By now the rival has given his Pokemon some decent moves and gotten his old Pokemon to their final forms. Kadabra replaces Fearow now. Though still not terrific by any stretch of the imagination, various moves might be a problem if they catch you off guard so beware. A good idea is to have an Electric-type on your tea; the majority of his team will fall to a fast Thunderbolt. Get rid of Kadabra as soon as possible: Psybeam can wreck your team with its speed and precision or confuse you if you stay alive.

Rival Sandslash Kadabra Ninetales Magneton Vaporeon
Battle Type
Single Battle
Items
Level 35 Level 35 Level 37 Level 35 Level 40
Attacks:
Slash
Sand-Attack
Poison Sting
Swift
Attacks:
Confusion
Disable
Psybeam
Recover
Attacks:
Ember
Tail Whip
Quick Attack
Roar
Attacks:
Tackle
Sonicboom
Thundershock
Supersonic
Attacks:
Water Gun
Quick Attack
Bite
Aurorabeam
Evolve Into Vaporeon
Rival Sandslash Kadabra Cloyster Ninetales Jolteon
Battle Type
Single Battle
Items
Level 35 Level 35 Level 37 Level 35 Level 40
Attacks:
Slash
Sand-Attack
Poison Sting
Swift
Attacks:
Confusion
Disable
Psybeam
Recover
Attacks:
Withdraw
Supesonic
Clamp
Aurora Beam
Attacks:
Ember
Tail Whip
Quick Attack
Roar
Attacks:
Thundershock
Quick Attack
Double Kick
Pin Missile
Evolve Into Jolteon
Rival Sandslash Kadabra Magneton Cloyster Flareon
Battle Type
Single Battle
Items
Level 35 Level 35 Level 37 Level 35 Level 40
Attacks:
Slash
Sand-Attack
Poison Sting
Swift
Attacks:
Confusion
Disable
Psybeam
Recover
Attacks:
Tackle
Sonicboom
Thundershock
Supersonic
Attacks:
Withdraw
Supesonic
Clamp
Aurora Beam
Attacks:
Ember
Quick Attack
Bite
Fire Spin
Evolve Into Flareon
Encounter #7 - Route 22

Location: Route 22

Details:
This match might be a little nostalgic if you didn't pass up on his second challenge earlier in the game. By now you should know what you're doing; whatever it is, keep doing that! Kadabra has a frighteningly strong Psychic attack and Sandslash never misses when Swift is used. Exeggcute has the annoying Poisonpowder/Leech Seed combo. If he uses a Jolteon watch out for Agility - it will ensure this thing is the fastest Pokemon in battle. Flareon gets Flamethrower which has very high base damage and can burn. Vaporeon will Acid Armor to make it impervious to physical attacks. This team is a good warm up for the Elite Four...and the champion after that.

Rival Sandslash Kadabra Exeggcute Magneton Ninetales Vaporeon
Battle Type
Single Battle
Items
Level 47 Level 50 Level 45 Level 45 Level 47 Level 50
Attacks:
Slash
Swift
Fury Swipes
Poison Sting
Attacks:
Psybeam
Psychic
Reflect
Recover
Attacks:
Leech Seed
Stun Spore
Poisonpowder
SolarBeam
Attacks:
Thundershock
Thunder Wave
Supersonic
Swift
Attacks:
Ember
Tail Whip
Quick Attack
Roar
Attacks:
Hydro Pump
Aurora Beam
Haze
Acid Armor
Evolve Into Vaporeon
Rival Sandslash Kadabra Exeggcute Ninetales Cloyster Jolteon
Battle Type
Single Battle
Items
Level 47 Level 50 Level 45 Level 45 Level 47 Level 50
Attacks:
Slash
Swift
Fury Swipes
Poison Sting
Attacks:
Psybeam
Psychic
Reflect
Recover
Attacks:
Leech Seed
Stun Spore
Poisonpowder
SolarBeam
Attacks:
Ember
Tail Whip
Quick Attack
Roar
Attacks:
Withdraw
Clamp
Supersonic
Aurora Beam
Attacks:
Thunder
Thunder Wave
Pin Missile
Agility
Evolve Into Jolteon
Rival Sandslash Kadabra Exeggcute Cloyster Magneton Flareon
Battle Type
Single Battle
Items
Level 47 Level 50 Level 45 Level 45 Level 47 Level 50
Attacks:
Slash
Swift
Fury Swipes
Poison Sting
Attacks:
Psybeam
Psychic
Reflect
Recover
Attacks:
Leech Seed
Stun Spore
Poisonpowder
SolarBeam
Attacks:
Withdraw
Clamp
Supersonic
Aurora Beam
Attacks:
Thundershock
Thunder Wave
Supersonic
Swift
Attacks:
Flamethrower
Leer
Fire Spin
Smog
Evolve Into Jolteon
Champion - Blue

Elite Four: Rival
Specialty: None

Details:
The circle is now complete. Your first and last challenge is with your rival, and he'll have just as many tricks as ever to face you. With a fully rounded out team you'll be hard pressed to find one Pokemon to take everything out. Balance everything out as always: don't train just one Pokemon (seriously don't) and make sure your type coverage is astute. Ninetales and Cloyster will try to trap you with Fire Spin and Clamp respectively, Sandlash hurts Grass-types with Poison Sting and Earthquakes anything that it doesn't miss, Exeggutor only has one damaging attack (the Normal-type Barrage), and Alakazam has fearsome Psychic power. Pay extra attention to his starter, who always has dual coverage (Poison/Fire for Flareon, Bug/Electric for Jolteon, and Water/Ice for Vaporeon) and an extremely strong STAB move. One approach to this is to just use Toxic on everything (use PP Up if you're doing this) and stall it out with Chansey or another bulky Pokemon. It's not exactly enthralling but if it's what works go for it. Good luck!

Champion Blue Sandslash Alakazam Exeggutor Magneton Ninetales Vaporeon
Battle Type
Single Battle
Items
Level 61Level 59Level 61Level 63Level 61Level 65
Attacks:
Earthquake
Slash
Poison Sting
Fury Swipes
Attacks:
Psybeam
Psychic
Kinesis
Recover
Attacks:
Barrage
Hypnosis
Stomp
Leech Seed
Attacks:
Thunderbolt
Thunder Wave
Screech
Swift
Attacks:
Fire Spin
Tail Whip
Quick Attack
Confuse Ray
Attacks:
Hydro Pump
Aurora Beam
Quick Attack
Mist
Evolve Into Vaporeon
Champion Blue Sandslash Alakazam Exeggutor Ninetales Cloyster Jolteon
Battle Type
Single Battle
Items
Level 61Level 59Level 61Level 63Level 61Level 65
Attacks:
Earthquake
Slash
Poison Sting
Fury Swipes
Attacks:
Psybeam
Psychic
Kinesis
Recover
Attacks:
Barrage
Hypnosis
Stomp
Leech Seed
Attacks:
Fire Spin
Tail Whip
Quick Attack
Confuse Ray
Attacks:
Ice Beam
Spike Cannon
Aurora Beam
Clamp
Attacks:
Thunder
Thunderbolt
Quick Attack
Pin Missile
Evolve Into Jolteon
Champion Blue Sandslash Alakazam Exeggutor Cloyster Magneton Flareon
Battle Type
Single Battle
Items
Level 61Level 59Level 61Level 63Level 61Level 65
Attacks:
Earthquake
Slash
Poison Sting
Fury Swipes
Attacks:
Psybeam
Psychic
Kinesis
Recover
Attacks:
Barrage
Hypnosis
Stomp
Leech Seed
Attacks:
Ice Beam
Spike Cannon
Aurora Beam
Clamp
Attacks:
Thunderbolt
Thunder Wave
Screech
Swift
Attacks:
Flamethrower
Quick Attack
Smog
Fire Spin/a>
Evolve Into Flareon