Is there any possible way to play Pokemon Emerald on the 3ds compatible systems? I am trying to get mew on ultra sun and there seems to be no other way then get it on emerald and transfer to ultra sun.
No.
Unless you hack your 3DS or something there's is no vc release for that game
you can play emerald in a Nintendo DS/DS Lite if you have a emerald cartridge it has a retrocompatibility with GBA Games
Sadly not, GB cartridges need the slot at the bottom of the ds which was unfortunately not included in the 3ds models. Only 2 ds’s, game boys etc.