This glitch is very GR8
But I didn't find this glitch.
If you want to see a better tutorial than this one, watch the one by Scykoh

e1 - When you select a name from that Popular names menu, it writes the RAM in a different way depending on which item you choose on the list when you choose a name. When you select ASH and BLUE it writes the RAM on the gameboy (or select emulator) in a way that this glitch will work. There is another way to do this glitch where you can name you and your rival anything you want, but I find this method a lot easier.
e2 - The timing for when you reset (reboot) the game is very sepcific. You find it yourself. The best way i can describe it is that you have to reset between the time that the YES NO box disappears and before the text that says WOULD YOU LIKE TO SAVE THE GAME changes. It'll take a while to find that specific timing though. For me it took a solid like 20 tries. Just be persistent.
e3 - Select any one Pokemon in slot 1-9 (all the onscreen slots) and move it to slot 10 (first offscreen slot) Then take the Pokemon from slot 11 (2nd offscreen slot) and move it to slot 9 (last onscreen slot). Then press B to exit the menu.

The software i use
DaVinci Resolve 12.5.1
(resolve12.5.1)
GNU Image Manipulation Program 2.8
(GIMP2.8)
VisualBoy Advance - M878
(vbam878)
Open Broadcaster Software 15.4 Studio
(obsstudio15.4)
I am not affliated, sponsored or endorsed by any of these software or their respective developers.

This video is not affiliated, sponsored or endorsed in any way by
The Pokemon Company
The Pokemon Company international
Nintendo Co., LTD.
Game Freak Inc.
Creatures Inc.

Pokemon is owned by
The Pokemon Company
The Pokemon Company international
Nintendo Co., LTD.
Game Freak Inc.
Creatures Inc.

All borrowed assets of this video belong to their respective owners and I do not claim ownership over any of the assets in this video.