the 2ds uses 3ds firmware so can run 3ds games (obviously without the 3d effects)
Its backwards compatable with ds/dsi games.
if your wanting to play normal ds/dsi games on it the the ace 3ds pro is a solid cheap option.
if your wanting to play 3ds games then the gateway card is an option.
this is a more complicated and expensive road to go down. the console has to be on a certain firmware.
i would speak to @spud1966 before parting with your cash, he has one and knows all the ins and out...