It actually has a good shot.
Since the PS2, there have not been that many big fighting series. We have had Super Smash Bros, Street Fighter, Mortal Kombat, Tekken, Soul Calibur, Marvel vs Capcom, Injustice, and some anime fighters.
We can say with some certainty that Pokken will not surpass Super Smash Bros 4 Wii U or Mortal Kombat X, which are already at about 3.5 million and 2.3 million. Street Fighter 5, even if only on the PS4, should also sell at least a few million. However, Soul Calibur 6, if released is likely to do poorly, especially since the series has generally had less praise and sales. SC2 sold 4.5 million, SC4 sold 3 million, and SC5 sold 1.3 million. Tekken has also been in decline, and Tekken 7 could easily sell under 2 million considering the long gap since Tekken 6. Anime fighters have also been declining; Naruto ended a few months ago, and Dragon Ball Z declined after 2010. Marvel vs Capcom 4 is not a certain hit, and Injustice may not get a sequel.
So in review, Pokken could possibly get into the top few fighters of the generation by selling only a bit over 2 million copies. Can Pokken sell that many on just the Wii U? Well, the Pokemon franchise has had successful spinoffs before. Even ignoring the N64 era of Pokemania, there have been the Mystery Dungeon games on handhelds, Stadium-like games for the GameCube and Wii, the Pokemon Ranger trilogy, PokePark, the Rumble series, and Conquest. These have ranged in total sales and quality, but I can picture a solid fighter from a known series selling 2 million or so. Especially since Hyrule Warriors shows how powerful a brand can be on the Wii U.
