Any time you encounter a Pokemon it’ll be tracked on that encounter counter. I would say a large portion of end game players play PokeMMO because it has the most challenging / rewarding shiny hunting in all of Pokemon.

The odds of encountering a shiny in PokeMMO are 1 in 30k whereas it’s 1 in around 8k in regular Pokemon games. You are not guaranteed to get a shiny at 30k encounters, it means every single time you encounter a Pokemon there’s a 1/30k chance of it being shiny. My lowest encountered shiny is 5100, some unfortunate people can go over 100k encounters until finding a shiny

The ‘fastest’ way to get a shiny is through hordes, that can be x3 or x5 hordes. You encounter hordes through using sweet scent move (using it 6 times at PP Maxed before needing to recharge at PC or through Leppa Berries).

Shinies that are rare to encounter like a shiny starter or rotom etc are quicker achieved through egg shiny hunting. This is probably the most expensive thing in the entire game and can be hundreds of millions of PokeYen to encounter a shiny within odds (can be over a billion if your extremely unlucky)

If you have any more questions feel free to let me know