Summary
Brock has evolved from a powerful Rock-type Gym Leader to become a skilled Pokémon Doctor with healing abilities. Comfey, given to Brock in the Alola region, is used to heal and soothe wild Pokémon, not for fighting. Brock's team includes many diverse Pokémon such as Sudowoodo, Geodude, Marshtomp, Ludicolo, Blissey, Crobat, Croagunk, etc.
inside Pokémon anime, Brock is second only to Ash in the number of episodes he appears in. While Brock's character's journey gradually took him away from fighting to become a Pokémon Doctor, he still served as a Gym Leader and possessed some pretty powerful powers. Pokémon.
Despite starting out as a Rock-type Gym Leader, Brock's Pokémon come in many different types, showing how much he has grown and expanded his knowledge throughout his journey. In addition to Rock, Brock also has quite a few Water-type Pokémon that he has used a lot over the years. After deciding to become a Pokémon Doctor, Brock also began specializing in Pokémon with healing abilities, helping him work more effectively.
10 Comfey is for healing, not fighting
First appearance: Pokémon Sun & Moon, “Heart of Fire! Heart of Stone!”
Comfey was given to Brock by Nurse Joy after he traveled to the Alola region and helped her escape an emergency situation using his Pokémon Doctor skills. Comfey are commonly used in the Alola region for their healing powers, as even the scent of Comfey is said to have restorative properties. Brock only used Comfey once, it was able to calm a raging Kangaskhan and stop it from going on a rampage with Sweet Scent.
Given that Comfey comes directly from Nurse Joy, it's clear that Comfey was never used in battle.and Brock never tried to get Comfey to actually fight. It won't be of much use in trainer battles, but it clearly has applications in situations with wild Pokémon, which can have unpredictable behavior, especially if they believe someone is invade their territory.
9 Sudowoodo grew up with Brock
First appearance (as Bonsly): Pokémon Ruby and Sapphire, “From Cradle to Save”
Brock first met Sudowoodo as a Bonsly in the Kanto region, during the Battle Frontier story arc. Brock noticed that Bonsly was hungry and crying, so he prepared some food to feed it to cheer it up. Bonsly has a fiery spirit and demands that Brock fight it before it follows him. Bonsly was the only Pokémon that Brock brought with him to Sinnoh, proving that the two had developed a strong bond.
Bonsly is not good at fighting but becomes much stronger after evolving into Sudowoodo. Now stronger and more independent, Sudowoodo is on a mission to repay Brock's kindness, becoming a valuable ally. Sudowoodo proved to be much stronger, defeating several opponents in Diamond & Pearl, but never reached the heights of some of his other Pokémon.
8 Geodude was one of Brock's first
First appearance: Pokémon: Indigo League, “Showdown at Pewter City”
Geodude has accompanied Brock since the beginning of the series, one of his first two Pokémon alongside Onix. Geodude is a realistic type of Pokémon, often quite serious compared to many other Pokémon in the series. Geodude's performance in battle varies, but its strong bond with Brock means it remains with him for quite some time. Geodude often proves useful in other ways, helping to put out fires or dig underground paths.
Brock eventually lent Geodude to his younger brother, Forrest, when Forrest took over Pewter City's Gym, but seemingly reclaimed it by the time of Sun & Moon. Geodude is often used when the Onix's large size makes it impractical, such as on ships or indoors, but the Onix is generally a better fighter.
7 Marshtomp gave Brock some variety
First appearance (as Mudkip): Pokémon Ruby and Sapphire, “Mudkip Quest”
Brock's Marshtomp first appeared as a wild Mudkip, helping the Mudkip breeder care for the many newborn Mudkip cubs in his possession. It then decides to join him and eventually evolves into Marshtomp, giving it much stronger powers. Mudkip is not the first non-Rock type that Brock has had, but he has used it more often and its Water-type properties have made it a valuable member of his team.
Marshtomp shares many similarities with Brock, fawning over female Pokémon in the same way that Brock often fawns over girls. However, it may be more mature, possibly from watching over baby Mudkip, helping Pokémon resolve disputes over food and the like. Marshtomp never actually won any notable battles after evolving, but it was still a bit stronger than before.
6 Ludicolo is a stupid but happy companion
First appearance (as Lotad): Pokémon Ruby and Sapphire, “The Lotad Lowdown”
Brock first encountered Ludicolo as Lotad early in Hoenn, where it had difficulty using the Water Gun. Brock helped it learn and after defeating Team Rocket, he decided to go with him. Lotad would eventually evolve into Lombre, when it was mistaken for the local “god” and helped bring rain to the surrounding area. It will re-evolve after coming into contact with the Water Stone, becoming the happy and lucky Ludicolo.
Ludicolo is often used in conjunction with Marshtomp, with Brock ordering both of them to use Water Guns to double their strength. Ludicolo hasn't seen too many battles in its fully evolved state, but its form makes it a good choice to cover up the weaknesses of many of the other Pokémon on Brock's team. Although Ludicolo's full power has never been demonstrated, it can be confident that it can pack a punch when needed.
5 Blissey is stronger than it looks
First appearance (as Happiny): Pokémon Diamond & Pearl, “One Big Happiny Family”
Brock won Happiness in the form of an egg after winning a contest to wear Pokémon's weirdest costume. He hatches the egg a few episodes later and reveals the Pokémon inside is Happiness, the child form of Chansey and Blissey. With Brock's later decision to become a Pokémon Doctor and Chansey/Blissey's association with Nurse Joy, it became quite fitting. Happiness has a surprisingly powerful Pound attack, winning several early battles with it.
In fact, Brock's Blissey is unusually strong overall. It is capable of lifting large boulders as Happiny, and once picked up Dawn's Mamoswine. Once evolved, it becomes an even more capable fighter, although like Comfey, fighting is hardly Blissey's primary skill. Perhaps it uses its nutritious egg to help Brock heal injured and weak Pokémon like other Chansey and Blissey.
4 Crobat's speed has made it an asset
First appearance (as Zubat): Pokémon: Indigo League, “Clefairy and the Moon Stone”
Brock's first capture in the series, Zubat was actually captured off-screen, even Ash was surprised when Brock called it out. As a result, Zubat stayed with Brock for a long time and the two became quite close thanks to the good care Brock gave his Pokémon. This eventually allowed Zubat to evolve into Golbat, and eventually Crobat, which can only be obtained with high friendship. Zubat often uses his Super Sonic to confuse his opponents, forcing them to attack each other.
Like Ludicolo, Crobat doesn't have many opportunities to show off as a fully evolved Pokémon, but Crobat is generally considered a fairly strong Pokémon.. Its speed allows it to surpass even Ash's Noctowl, and that combined with its good hearing makes it an excellent scout, helping to track down Pokémon stolen by Team Rocket.
3 Croagunk's fighting skills make it strong
First appearance: Pokémon Diamond & Pearl, “Gymaliar!”
Interestingly, Brock's Croagunk first bonded with Team Rocket before being captured by Brock. Croagunk proved to be quite proficient in combat and Brock used Croagunk as his first choice in many situations after acquiring it. Croagunk became famous for dragging Brock away when he got too enamored with girls, often using Poison Jab on him in these situations, which helped Brock stay in line. Despite this, Croagunk and Brock are quite close and often get along well in battle.
Croagunk brought more new typings to Brock's team, helping to transform his Pokémon even further. Croagunk's senses were eventually adjusted, making it capable of detecting approaching danger and allowing it to react quickly to situations. This, combined with its skills, makes Croagunk quite a competitor and it's easy to see why Brock trusts it so much.
2 Fortress bursting with happiness
First appearance (as Pineco): Pokémon: Gold & Silver, “Going Apricorn!”
The only Pokémon that Brock caught in Johto, Pineco is an enthusiastic Pokémon that has a tendency to Self-Destruct when experiencing strong emotions. Pineco has incredible stealth abilities, being able to lower itself from trees using thin threads of silk. It develops in dramatic directions as Brock falls into danger while trying to protect it from Team Rocket, and becomes much stronger as a Forretress.
Forretress has learned Rapid Spin, allowing it to clear hazards and eliminate opponents who might try to latch onto it, and can set up its own hazards with Spikes. Its ability to attack steel makes it a surprisingly tough Pokémon, often withstanding attacks from Team Rocket's Pokémon with ease. The Forretress did not see many battles that did not involve Team Rocket, but its performance against the trio made it invaluable during their early days traveling through Hoenn.
1 Steelix can massively evolve
First appearance (as Onix): Pokémon Indigo League, “Showdown at Pewter City”
Onix is the main challenge Ash faces when he first challenges Brock due to its size. While that size sometimes makes fighting impractical, it is also one of Onix's greatest assets, allowing it to overpower many smaller Pokémon. This is Brock's first Pokémon, given to him as a gift by Brock's father when he was 10 years old, much like Pikachu was to Ash. Onix has a major weakness to water, which is often the only way it can be defeated. It evolved into Steelix under the care of his brother Brock and his successor as Gym Leader, Forrest.
In Sun & Moon, it is revealed that Brock has regained his Steelix and together they have mastered the art of Mega Evolution, allowing it to transform into Mega Steelix. Mega Steelix demonstrated its strength by easily defeating Kiawe's Turtonator, even after Kiawe used a Z move against it.. Steelix knows many different moves, which helps it fight against all types of Pokémon, and its ability to hit steel gives it very few weaknesses. Its keystrokes, Mega Evolution ability, and variety of moves make Steelix solid Brock's strongest Pokémon.