They cannot run on a DS or DS Lite, and they cannot be played in a standard NDS emulator (like DeSmuME, NO$GBA, etc.).
If you want to play Gen 6 on a , it's impossible — you would need a 3DS or 2DS. pokemon gen 6 nds rom
Would you like a guide on setting up for Gen 6 instead, or recommendations for DS ROM hacks that include Gen 6 Pokémon? They cannot run on a DS or DS