I got on my mind that in holidays like xmas or easter they could add tematic hordes (like delibird or exeggcute) just for a limited time. This would be a great thing for the players that have shiny hunting as focus on game. I know that we are not the most of players but i never saw something like this on pokemmo.
This would work like community day in pokemon go but without increase the shiny odds just add a limited time horde for more efficient hunting.
I dont know if make this is viable but i'm sure that many people will be happy with.