>>54140791They literally can't. There is no distinguishable difference between an injected pokemon and a legitimately caught pokemon if done correctly.
The only time that it is "caught" is when the injectors are stupid as fuck. These are still legal pokemon, but it's pretty clear that they didn't hit lottery odds six times in a row.
But as long as the current save files are the way they are, and you're allowed to bring in older generation mons from games where you can RNG manipulate, nothing will change.
My hot take would be: Gen X should be a hard reboot of the franchise. Redo Kanto and Johto (call it Aurum Red and Argent Blue or some shit) completely, put in all the mon changes and fixes they want, and then say "from this point on, you can only use mons from Gen X and beyond". Then they can do Pokemon Legends Celebi/Ho-oh or whatever to add in new regional forms.