When do spawns return to normal?

I want it to last at least until I catch a shiny Growlithe

I also want it stay. Normally i never find wild Tangela. Rhyhorns in wild barely exist. And i also want shiny Geodude, Growlithe and Grimer...

And im happy to avoid see those crappy Whismurs, Sentrets or Hoothoots.

So you want the increased spawns for Tangela, Porygon, Dratini, Hitmonchan/lee, Chansey, Lapras, and all the potential shinies to go back to just being Pidgey, Whismur, and Wurmple sooner rather than later? Yeah, let's get right on that! /s 🤣

Some people just can't be pleased.

You should be collecting Rhyhorn, Magnemite, and Tangela like crazy for Gen4, trading them until you get a lucky one, and then dominating G4 with them. Chansey and Dratini are also good on principle to have more of. I just wish that Swinub could come to the party.

You found wishmur more exciting than Lapras? Say what? Gen1 is has been the prime for most of the Pokemon player base.