Bruno

Bruno is a PokéGod. It is a real Pokémon named Snubbull, but before Pokémon Gold and Silver came out, it was known as Bruno.

Origin
Bruno, later known by its Japanse name Buru, was once thought of as just a fake PokéGod, but fans later learned that  Bruno was not its real name. The correct name was Buru, which it was called for the remainder of the time before Pokémon Gold and Silver versions.

Location
There were a few methods of capturing Bruno:

Go to the Unknown Dungeon and swim to the right of it. Use the ItemFinder and you will find find the Bottle. Take the Bottle to Pr. Oak and he will read the note, which says that there are many secrets to the Unown Dungeon and you will never find them all until you find a dog. Bring five PokéGods to the spot where Mewtwo once stood and you will see a boulder. Use Strength on the boulder to reveal a staircase. Going down the staircase reveals six platforms, each with a Pokémon on it. One of these is Bruno. It changes position each time and once you choose one, you can't get the other five. However, if you go up the stairs and back down, you will have another chance at catching Bruno. This is similar to the method of capturing the Legendary Beasts in Pokémon Gold and Silver.

Use a Water Stone on Growlither and it will evolve into Bruno.

Trade a Pokémon between a Japanese Yellow Version and an American Blue Version to create a glitch, which will give you Bruno, called Buru at this time.

It can also be obtained in a similar manner to Golbitrog.

Pokédex
Bruno is number 635 in the Pokédex.