Brock is originally the Gym Leader of Pewter City Gym but decided to follow his dream to become the greatest Pokémon Breeder he can be. After his defeat from Ash Ketchum, he quickly gave up his title. He accompanied Ash on his journey for quite some time, all while trying to live up to his goal. He currently wishes to be a great Pokémon Doctor.
Brock's most notable feature about his appearance is that his eyes naturally appear closed. The rare times people see them open are when they are forced open unnaturally, such as these examples from what happened in the anime: a hit with Charmander's Flamethrower in The Ninja Poké-Showdown, when being hit in the back of the head by Arbok's tail in Who Gets to Keep Togepi?, and when he makes a face for Larvitar in A Crowning Achievement. This has been the center of fan attention for a long time. He also has spiky brown hair and tan skin, notably darker than the skin of any other major character in the anime (until Iris in the Best Wishes series).
Along with Tracey, Cilan, and Kiawe, Brock is the tallest of Ash's traveling companions and the closest to looking like an adult. Next to actual adult characters, however, it is clear that he is still a teenager. Not counting temporary outfits, he has worn three different outfits, all of which have had the colors orange, green and brown, with blue shoes.
Original series Edit
In the Original Series, Simpsons Guy 4, the second half of the Franklin Expeditions series, and Road to the Omniverse, he wore an orange t-shirt, a lime green cargo vest with 4 pockets, a dark brown belt with a gold buckle and dark red pockets, brown jeans, and blue-gray sneakers with white trim.
His original outfit is also seen during flashbacks throughout the anime series' run.
Advanced Generation Edit
In the Advanced Generation Series and Uncle Funtime 4, he appeared in a new outfit, which consisted of a brown short-sleeved jacket with orange trim, a green short-sleeved undershirt, grayish-brown cargo pants, and indigo sneakers with light blue trim.
Diamond & Pearl Edit
In the Diamond and Pearl series, Uncle Funtime: Thanksgiving Edition, the first half of the Franklin Expeditions series, and Anime Christmas Extravaganza, he wears yet another new outfit, consisting of a green collared shirt, an orange vest with brown trim, khaki pants with knee stitching, and blue high-top sneakers.
Sun & Moon Edit
In the Sun & Moon series, Brock's old outfit in the Original series has minor changes. His lime green cargo vest lacks the two pockets in the edge of both sides making his vest turned into a denim vest.
During the Gym battle against Kiawe as he mega evolves his Steelix into Mega Steelix, Brock was in shirtless which he removes both his lime green vest and his orange t-shirt making him resemble his counterpart in both games, Pokémon Red and Blue as he reveals to wear a necklace with a Key Stone embedded as a pendant where he later removes it to activate his Key Stone to mega evolve his Steelix.
During his and Misty’s visit in Alola, he wears a cloudy blue sky and plain landform-theme buttoned shirt, beige short pants and blue shoes.
Virtual Paradise Edit
In the Virtual Paradise, Brock wears a loose orange Hawaiian button shirt with light peach flowery designs and a black wristband on his left wrist, green denim capris and blue sneakers with a white trim.
Heroes United Edit
In the flashback featured in "Snow-Shoveling as a Team! You Can't Help Everyone!", Brock wears his orange t-shirt underneath a green jacket with darker green trim, a brown belt with a silver buckle and brown pouches, light brown cargo pants with gold and white striped cuffs, and blue and light green sneakers.
Brock is considered the most mature, wise, and levelheaded of the main characters, and he is arguably the most intelligent character as well. He often acts as an older brother and caretaker to the other characters and a voice of reason in disputes. He will usually place others before him and will help and support his friends even against his better judgment or at his own expense. While he is not shown to battle often, he can understand the situations and strategies in any Pokémon battle, and often explains them to the other characters, probably because he was once a Gym Leader. His wisdom is possibly derived from how observant he is; he can tell just by sight how a Pokémon is feeling.
Brock always carries books and maps with him and thus, is usually the character who knows where the group is headed and what they can do when they get there, though in the Advanced Generation series this role was mostly taken over by Max, who owns a PokéNav. He also carries a lot of other supplies, such as Potions, Pokémon food, and a set of cookware, as well as practical tools like a brush and pocket knife; in The School of Hard Knocks, the extent of his preparedness and comically large capacity of his bag was demonstrated, as he pulled a table and full tea set out of his backpack. He is a domestic, and grooms not only his Pokémon but also those of his friends with whom he travels. He handles all the cooking and cleaning for his friends.
Despite this, all his maturity and rationality leaves him completely when he catches sight of a beautiful woman. Brock has a desperate need for female companionship, which grows worse as he fails to gain it. He will do anything and everything he thinks will impress women, which inevitably ends with his heart being broken every time. A few women have shown interest in him as well, such as Wilhelmina, Temacu, Natalie, Lucy, Holly, Autumn, Narissa and Lizabeth, but most others do not notice him or are not interested.
No matter how many times he is disappointed, though, Brock remains determined to find a girl to start a relationship with and has indicated several times he would stop traveling with Ash and stay with the girl if this happened. He also likes both Nurse Joy and Officer Jenny. This behavior tends to wear on the nerves of other characters, and Misty and Max have both commonly dragged Brock away from women by his ear. Some of Brock's own Pokémon, most notably Croagunk, have attacked him for getting too flirtatious with women and dragged him off as well as punishment for his behavior.
His goals have played a passive role in his character's activity and development, and his role has generally been one as support for other main characters, usually contributing more in terms of wisdom and comedic antics than the action of the series. Unlike other characters, who aspire to achieve and excel in competitive fields like Pokémon training and Pokémon Contests, his aim to become a great Pokémon Breeder is a quiet one and thus does not get showcased frequently. This caused him to question if he was actually pursuing his dreams like his friends were near the end of the Diamond & Pearl series and ultimately lead to him deciding to become a Pokémon Doctor instead. His other goal, to find a girlfriend, is similar to Team Rocket's quest to capture Pikachu, in which both are for comedy and thus doomed to fail.
Upon his family, he is very caring towards his siblings including his younger brother, Forrest and has a great respect for his father, Flint. In A Family that Battles Together Stays Together! and Grating Spaces! He also shows his anger and disdain towards his mother, Lola who is responsible for remodeling the Pewter Gym into an aquatic gym, as well as her ditzy behavior.
Simpsons Guy 4: The Pokemon Daze Edit
Pokemon: Thanksgiving Edition Edit
Brock goes to the Thanksgiving party in Hingham with Ash and co.
School Daze 2: A Jolly Good Battle Edit
Brock watches the Regular Show finale with Ash and co.
Pokemon: Franklin Expeditions Edit
Uncle Funtime 4: A Series of Excitement Edit
After dealing with stress from constantly working for his family and as a doctor, Brock decides to take a break and meet up with Ash, May, and Max in Franklin. Together, they go to Boston and New York City before parting ways at the end of the summer.
Brock doesn't appear in "Weekend at Gammy's", but he does appear in a few flashbacks.
Christmas Chronicles 2: Anime Extravaganza Edit
Ash and co. greet Dawn as she returns to Pallet Town to attend a Thanksgiving dinner planned by Ash's Mom. However, those plans change as Dawn finding a picture of Ash and Alex. The gang decides to go back to Franklin to see Alex. When they got to Franklin, Tom and the gang introduces themselves to Dawn. After spending a whole week together, they end up going to Thanksgiving dinner with the Connellys. After Thanksgiving, Brock and his friends decide to spend all of December in Franklin with the Connellys so they can go to Cape Cod during Winter Break. During the whole series, Ash and co. go on many crazy adventures while meeting Team 7 and the Straw Hats and celebrating the Holidays before paring ways.
School Daze 4: Road to the Omniverse Edit
Brock is taken to an alternate timeline based on the original Pokemon video games. However, unlike the others, Brock doesn't lose his memory, and because of this, Brock holds him hostage in his own gym. Ash rescues Brock after beating Eon in a Pokemon battle. Afterwards, Brock helps the gang take down Eon before parting ways.
Heroes United Edit
Brock and Misty are watching television, when they hear that they have to go to the movies, much to their dismay. When they get to the movies, the place is suddenly overrun by Zombiens. Dan and Susan are bitten, and turned into Zombiens, while the rest of the gang is struggling to find a way out. Brock and Misty take a subway and escape. Their current whereabouts are unknown. He appears in a couple flashbacks in HU008 and HU019.
- Brock's personality reflects Uxie's one; the Knowledge Pokemon.
- In the Pokémon DP Special, Brock has photos of Ash, Misty, May, Max, Dawn, Pikachu, and Piplup to remind him of his past journeys through Kanto, Johto, Hoenn, Kanto's Battle Frontier and Sinnoh.
- Brock is a very talented cook, especially when it comes to making food for Pokémon (this is related to the fact he is a Pokémon Breeder).
- In the episode A Crowning Achievement, Brock actually temporarily opens his eyes in a flash second to try to cheer up Larvitar.
- Brock's eyes are rarely open, excluding the examples shown.
- At the beginning of the anime, Brock didn't show a lot of interest in girls. After a while, he finally shows it.
- Brock has appeared in every season except for the Best Wishes ones and the XY ones, although he only appears in flashbacks with Dawn and Ash.
- As seen in the episode Taming of the Shroomish, Brock is apparently afraid of ghosts. While he and May were shopping, she heard of a haunted mansion. He was terrified just hearing about it, and, while May was overjoyed, she literally had to drag him there. Whenever he heard somebody talking about ghosts, he leaned away. He was afraid of the mansion and showed dismay and horror when they talked about advancing inside. He was fine once he found out that the ghosts were actually Shroomish, though. He was also fine on Ghoul Daze!, among other episodes.
- Brock's real dream is to become a Pokémon doctor. However in "Jirachi: Wish Maker", he said he wanted to become a magician because he could make "beautiful girls appear out of thin air".
- He can notice the small things that make each Nurse Joy and Officer Jenny physically different.
- It is said that Brock was taken out and replaced with Tracey due to the notion that he would be racially insensitive to Pokémon's growing worldwide audience. When it was revealed that said notion wasn't the case at all, they put him back in for Johto.
- Brock is currently the only travelling companion, other than Ash, to travel with all the main female travelling companions who are the playable character in the main game, with the exception of Serena in X and Y.
- In the anime, Brock owns both Geodude and Onix during Gym battles. The other one is Roark.
- Brock is the first main character to use Mega Evolution.
I don't own any of the information, it all came from: http://pokemon.wikia.com/wiki/Brock_(anime)