It's only possible if you have a cartridge, delete your entire switch save data, and can download 1.1.1 from a friend who has it already

I also ran catch shaymin, but with a different ruleset. This one ends the timer when you've successfully escaped flower paradise, in order to prove you haven't softlocked there.

That is a menu stack. Setting it up is slightly slower than double storage, which is what the runners do. It also allows them to run while still in the bag, and navigate to the save menu while still running.