If you're reading this, you probably know about Reverse Badge Order. I present to you Reverse Rival Order, which is exactly what it sounds like: Win all of the Rival battles starting with the Champion battle and ending with the 1st battle in Oak's lab. Any method of calling the battles would be acceptable as in Reverse Badge Order. Whenever I do Reverse Badge Order, I prefer to walk through walls to the gyms as I never got the hang of the the current method, so I am sure my route is a bit slow as I don't use room warps. I am aware that you can likely call every rival battle via bag underflow. This would be allowed as it is allowed in Reverse Badge Order.

Route:

1. Play up to Celadon City Abra using the usual any% strats.
2. Get whatever Pokemon you're going to use to win battles.
3. Walk Through Walls glitch to Indigo Plateau. (Or figure out another way to warp to Indigo Plateau, if you know a champion room warp, even better.)
4. Beat Champion.
5. Beat Rival 7. (Rival 7 does not appear when you don't have badges. You can use the Mew/Ditto Glitch with the correct special and number of Growls or Sword Dances to call the team. Must call the team that uses the starter that is better than yours.)
6. Beat Rival 6 in Silph Co. Walk Through Walls glitch around the Rocket blocking the Silph Co door.
7. Beat Rival 5 in Lavender Tower.
8. Beat Rival 4 in SS Anne. Can use Walk Through Walls to get around the Sailor checking tickets, or if you get Koga's badge, the Surf/Reset glitch.
9. Beat Rival 3 at Nugget Bridge.
10. Beat Rival 2 at Route 22.
11. Start a New Game and beat Rival 1 or call that battle using a glitch.
12. Time when exited out of the battle screen.

Alternate Route:

1. Get 8 badges to fight Rival 6 without glitching.
2. Call Rival 2 via a glitch or start a New Game, Beat Rival 1 and do Oak's Parcel to unlock Rival 2, beat Rival 2 and start a New Game again.

No need to start a New Game if using a glitch to call the Rival 1 battle, but it might be faster to do so depending on your setup.

Strongly suggest banning save corruption.

You may want to move this post over to red/blue category extensions (https://www.speedrun.com/pkmnrbext/forums). If you complete a run and have a well defined ruleset, then you can post the run in the same thread you start there and it can be considered to be added as a category extension. I am not too involved with glitched categories, but you may also get a quicker response on the psr discord (https://discord.com/invite/dRpzCBJsSM) if you have questions. That being said - sounds like a neat idea!

You actually need to beat Agatha in order to unlock the Champion fight, but that shouldn't be an issue.