If we're counting just the PS4 version of the standard SF5, then i expect SSBU will win.

Difficult to count PC. Most sales are digital and we rarely get figures.

Until we know how SF5 turns out its hard to say. But I'd suspect Smash will have the advantage.

Street Fighter V, even without PC. lol

Well it looks like VGChartz is tracking Street Fighter IV's sales on each platform with all the editions added up into one. You can't find Super Street Fighter IV or Ultra Street Fighter IV in the search, so clearly they've added them all up together under the blanket title "Street Fighter IV" for both PS3 and X360. (3DS is Super Street Fighter IV because that's the only version that released on it) So you'll probably have to count the extra editions of Street Fighter V as well in the long run. Also, we may never know exactly which game wins because SSB 3DS and SSBU are available digitally, and SF:V probably will be as well. 

If we only count WiiU-PS4, SFV wins by little, because of the difference of the installbase.
If we cont 3DS-PC, SSBB wins.
I don't know if Capcom will make new versions for SFV (that they will), and I don't know if they'll keep the exclusivity of those like Dead Rising 3or RE4.

You may be right, looks like the whole figure of SFIV are the many games. Now it makes it much less from sales

All SF V versions should count since they are the same game will added fighter, stage, clothes, modes... But all can be bought as DLC on the base version or disc package.

Mortal Kombat X will beat SFV.

SFIV sold 3.3m (http://www.capcom.co.jp/ir/english/business/million.html ) Not why sure this site has it sooo overtracked.

MK9 did 4m~

Smash will beat both of those tho.

Thankz^

Looks like vgc tracked new games and combined them with the original. Its like if Pokemon third versions combine with the new gen games.

SFV might sell more because of installbase but Smash 4 is far more accessible giving it much more appeal to the average person.