You're thinking of the Ditto Glitch, very much similar to the Mew Glitch. So instead of teleporting like usual, fly to FUCHSIA CITY, then walk to the east towards ROUTE 15, fight any trainer. Then walk into grass area until you encounter DITTO. Then switch to a Pokémon with a special of 226, battle or run [doesn't matter]. Immediately after the battle, return to the place where you first teleported. The start menu will open, then you will fight Prof. Oak. Lower his attack 4 to 6 times using Growl for him to have a Charizard, Venosaur, or Blastoise team.
Note 1: It is crucial that DITTO transforms into the Pokémon with a special of 226. After that it doesn't matter if choose to fight, just don't catch it.
Note 2: Its is important to use 4-6 growls for him to have his proper team.
And yes he has a connection to Elite Four. His team is identical to Gary's. Implying that the player was supposed to fight him at instead of Gary. But it makes more sense to fight Gary when you think about it.