DraStic

So I guess I'm screwed as well.

First time playing HeartGold and I didn't know you had to manually delete the old save before making a new one, so when I started a new game and it didn't let me save in-game I just started using the savestates.

Now, after 35 hours of not so easy "monotype challenge" gameplay, I'm left with a useless in-game save from another gameplay and a Johto completed savestate with no way of going to Kanto.

Yup, the pain is real my friend. Luckily I had a save halfway to that point so I didn't have to start 100% over.
Maybe there is something for you in starting over

Dunno if it helps, but I just made through Victory Road. My playthrough is vanilla-ish to a fault, so if you want to edit it to add some flair and play on, be my guest.

I already gave up, started from the working save file and I'm already at lt surge so it's all good I suppose lol