Can i use a cross save from japanese DS to american WII U SSB 4?

Specifically for SSB 4. I have a japanese ds XL and i intend on getting the japanese super smash bros which comes out in ....16 hours. However i have an american wii u and do not intend on buying a sepperate wii u just for the game. I know nintendo is allowing us to cross platform our saves from DS to WII U. I need to know if i am also going to need to buy the american SSB. This isnt a huge factor for me, im going to buuy the japanese one regardless. However nintendo is releasing the NDS XL in october and doesnt have a plan to release it at all this year in the US. I want to know if i should invest in the japanese handheld and be able to cross save or if it wont be compatible and i should just wait on that part.