As a Pineco, in its debut
Brock caught Forretress as a Pineco near Azalea Town. Having earlier expressed that Pineco's violently unstable temper and tendency to explode was both cool and a true challenge for a Pokémon Breeder, Brock attempted to capture one. However, he tripped on a rock and headbutted the tree, frightening the Pineco so much that they all exploded. Brock got his chance later, when Team Rocket was attempting to steal all of the Apricorns. The giant fan ended up blowing all of the Pineco out instead, and Brock managed to catch one in his arms before it hit the ground. However, the Pineco pried itself free and attacked Team Rocket, tackling the trio off their machine. It engaged in a battle against Jessie's Arbok alone, but could not match the powerful snake and began to flee. Maizie told Brock that he could capture the Pineco in the Fast Ball, which he did just as Arbok tackled, causing Arbok to crash into its Trainer. Once Pikachu drove Team Rocket away, Brock sent out Pineco and promised that they would be good friends. Pineco enthusiastically used Self-Destruct on its new friend.
In Ariados, Amigos, Brock volunteered Pineco and himself as a duo to train under Aya at the Pokémon Jujitsu Academy. However, Pineco was so startled by Brock's enthusiasm that it exploded in Brock's arms. Brock and Pineco later stunned everyone at the Technical class with Pineco's superb Spikes attack. Both were very happy to hear that they were in such perfect sync, and Pineco promptly exploded again.
Pineco and Golbat watched over Brock when he fell ill in Sick Daze. It also helped rescue all of the stolen Pokémon by attacking Arbok and Weezing, again with Golbat.
Pineco evolving and causing an explosion
In Entei at Your Own Risk, Pineco enjoyed a hot spring. However, it was not as quick as Misty's Staryu when Team Rocket tried to suck up all of the wild Pokémon, and was sucked up in a typhoon of water. Brock jumped after it, and he caught his Pokémon until a wild Ursaring crashed into him and knocked them apart. Upset by this, Pineco evolved into Forretress. Its evolution induced a large explosion which nullified Team Rocket's suction and allowed all of the Pokémon to escape. In the next episode, it prevented Team Rocket from stealing a King's Rock by using its newly learned Rapid Spin to trip them up and delay them long enough for Pikachu to get rid of them with Thunderbolt.
Its final Johto appearance was taking out the Hitmonlee belonging to Kail of the Invincible Pokémon Brothers with Rapid Spin, in one final battle between the three friends.
Advanced Generation series
In You Never Can Taillow, Forretress came to the rescue of Ash and his new friends, Max and May, sent out by Brock to use its newly learned Explosion to drive away a mass of attacking Taillow. Brock had given his brother Forrest most of his Pokémon (Onix, Geodude and Crobat), Forretress being the only Pokémon he took with him to Hoenn.
Forretress was seen quite regularly during the early Hoenn episodes, along with Torchic and Pikachu. However, it was rarely used as Brock's battling Pokémon, once he acquired Ludicolo and Marshtomp. He would send it out to use its Rapid Spin or Spikes to drive away hostile Pokémon or Team Rocket. It was used to battle James's Cacnea in Cheer Pressure, but was defeated when the cheer squad, led by Sheridan, cheated by having his Shroomish and Makuhita use Helping Hand on Cacnea.
It used Explosion in Going for a Spinda to defeat Team Rocket and save Claire's Spinda.
It was used in Where's Armaldo? in an attempt to talk down a restless Armaldo.
Kanto Battle Frontier
Brock kept Forretress in his team during the Battle Frontier saga.
In From Cradle to Save, Forretress battled a wild Bonsly. Its Rapid Spin knocked Bonsly out temporarily, but this was not enough to capture Bonsly. However, once Bonsly got up, it ran into the Spikes that Forretress had fired while Bonsly was unconscious, knocking it down again and this time allowing Brock to capture it.
Forretress was left at the Pewter Gym when Brock headed to Sinnoh.
Personality and characteristics
As a Pineco, it was very temperamental and tended to blow itself up and Brock along with it whenever it got startled, angry, or even happy. It was shown to be caring and helpful when it took care of Brock along with Brock's Crobat in Sick Daze. After it evolved into Forretress, it seemed to like Brock more, and began to act loyally.
| Using Explosion (Part 1)
| Using Spikes|
as a Pineco
| A † shows that the move was used recently, unless all moves fit this case or there are fewer than five known moves.
In the games
Brock uses a Forretress in Pokémon Stadium 2 Round 1 battle.
- Before leaving it in Pewter City when he left for Sinnoh, Forretress had been in Brock's party longer than any other main character's Pokémon, except for Pikachu, including the time when it was a Pineco. This record was matched and subsequently broken three episodes later by Jessie's Wobbuffet.
- It does have the record for being in a main character's party longest of all Pokémon that have been known to evolve during the anime.
- Forretress is the first Steel-type Pokémon to be owned by a main character.