Kaiser runs the Safari Zone and is best known as the warden from the banned episode "The Legend of Dratini." He's become infamous in fan discussions almost entirely because of his constant use of revolvers—particularly pointing them at Ash and firing them at Team Rocket—which led to the episode being pulled from Western broadcast. Since it only ever aired in Asia, he never received an official English name.
Thirty years before the episode, Kaiser found a rare Dratini in the Safari Zone. Word spread fast, and trainers came from everywhere hoping to catch it. The problem was that while hunting for this one Pokémon, they basically trashed the whole zone, catching tons of other Pokémon in the process. That's why Kaiser eventually set up the Safari Zone's famous rule: trainers get exactly thirty Safari Balls and a fishing rod per visit, and that's it.
Kaiser takes his job protecting Dratini seriously—maybe too seriously. He flatly denies the Pokémon even lives there and doesn't hesitate to threaten visitors with his revolver if they break the rules or ask too many questions about Dratini.
When Team Rocket captures him looking for Dratini's location, Kaiser actually holds out at first, even when they threaten him with his own gun. But Team Rocket eventually breaks him using a tickler mecha that forces him to give up the secret lagoon. Once he escapes, Kaiser finds Ash and warns him what's happening. At the lagoon, Team Rocket sets an underwater bomb to flush out Dratini. Kaiser and Ash dive in to stop it—Ash borrows Misty's Staryu to help Kaiser back up, then swims the bomb toward the surface himself. Running out of air, Ash gets saved by a Dragonair, which turns out to be the original Dratini from all those years ago. It even has a baby Dratini of its own. Seeing this, Kaiser breaks down in tears.
Content compiled by AnimeList.moe from publicly available sources.