~ Sebastian raging at Tim and Pikachu for attacking Charizard.
Sebastian is a minor antagonist in the 2019 comedy mystery film Pokémon: Detective Pikachu. He is the owner of an underground Pokemon fighting arena of whom holds a grudge against Harry Goodman's Pikachu.
Before the events of the film Sebastian began running an underground Pokemon fighting arena in Ryme City—where traditional Pokémon battling is considered illegal—and also raised and trained his Pokémon partner Charizard. At some point, his activities were discovered by Dr. Ann Laurent and Pokémon Comprehensive Laboratories, who began to supply him with the drug R (which causes Pokémon to go berserk), so that he could use it on the Pokémon in his arena and they could thus test it's effects.
Shortly before the events of the film, Harry Goodman and his Pikachu, in their investigation of R, came across Sebastian's arena and defeated him in a Pokémon battle, leaving him with a deep desire for vengeance against them after his Charizard was left with a scar from the battle.
During the events of the film, an amnesiac Pikachu was recognized by Sebastian and immediately he stormed towards Tim Goodman (Harry's son) and demanded a rematch between his Charizard and Harry's Pikachu. Tim then explained that the two were investigating the R chemical and wanted to know where it came from, Sebastian promised to tell Tim everything he knew on the condition that the rematch took place.
During the rematch Pikachu forgot all of his signature moves and was left attempting to escape Charizard's wrath. This got to a point in which Tim decided to step in and break up the fight, seeing this Sebastian warned Tim to leave the arena otherwise he could be killed to which the latter didn't listen. Sebastian then stepped in and walked towards the commotion to defend Charizard after Tim started helping Pikachu fight it. In the ensuing chaos Tim tackled Sebastian to the ground in turn accidentally smashing all of the vials of R Sebastian was holding in his coat's interior pockets spreading the chemical across all of the Pokemon in the arena. With all of the Pokémon around them being infected and becoming savages Tim demanded to know about the R with Sebastian replying that all he knew was that "The Doctor" had made the chemical and was supplying him with it, he then broke free of Tim's hold and fled the ongoing chaos advising that he do the same.
Sebastian is a dark-skinned man with black short hair and a goatee. He is always shirtless in spite of wearing a fur-collared trenchcoat (which has a large tear in it following his first encounter with Harry's Pikachu) and trousers, his body is also covered in tattoos; the most notable of which being the Charizard tattoo on his chest, in reference of his signature Pokémon.