If it's not compatible with the DSi, it's not compatible with the 3DS.
However, even some that are compatible with the DSi are not compatible with the 3DS.
However, even some that are compatible with the DSi are not compatible with the 3DS.
to be truthful even out of those that are compatible with the 3DS, they arent "truly" compatible. they just suck a less enough to function on the 3ds with no real features besides playing crappy quality ds games in ds mode on the 3ds which will probably get you banned once nintendo starts monitoring systems in may.
] On Guard 
