>>35515256The shiny mons that are from events often have exclusive moves from such events (Happy hour Shiny Jirachi for example) so in the moment that you see certain shiny mon you can tell which set is running your rival. The best example of it is Ash Greninja being unable to be shiny so a shiny Gren is always protean.
And you said, is a battle simulator so they want to keep the same rules from the real game to its own meta.
However if you want to use a shiny Zygarde in showdown you can use it in some metagames where all shit is allowed like Balanced Hackmons.
