Using official sales info from Nintendo, Pokemon SuMo has finally outsold a main title in the Pokemon franchise this quarter:

Pokemon SuMo at 15.67M and Pokemon BW at 15.64M

Source:   https://www.nintendo.co.jp/ir/en/finance/software/3ds.html

                https://www.nintendo.co.jp/ir/en/finance/software/ds.html

In fact, it's also worth mentioning Pokemon XY almost accomplished the same feat as well:

Pokemon XY at 16.15M and Pokemon RS at 16.22M

Source:   https://www.nintendo.co.jp/ir/en/finance/software/3ds.html

                http://www.neogaf.com/forum/showthread.php?t=963700

It's almost guaranteed that both XY and SuMo will surpass RS this holiday season, and while XY may be running out of steam, SuMo has a shot at outselling DP eventually, which is at 17.67M. (I personally think it will do so this holiday season as well)

Source:   https://www.nintendo.co.jp/ir/en/finance/software/ds.html

On the subject of Pokemon sales, both XY and SuMo are really undertracked here on VGChartz, do they ever fix these?

Edit: Of course, SuMo is probably going to outsell XY this holiday season as well

I don't see SuMo outsell DP. UltraSun/UltraMoon will cut it legs. Still has a shot to outsell gen 3 game though.

Gunned down by your own kind, sad really.

Ah, I was thinking along the lines of USUM would help sales of SuMo as well.

Unfortunately I don't know sales of BW after B2W2 launched, which would be the closest comparison we have. Knowing that would probably help for a more accurate estimate.

SuMo is going to be the best selling games for 3DS.

USUM will sell lower due to them being sequels and the Switch game being already announced

X/Y i9s just barely going to outsell RS, but that's it. But it's still amazing at those numbers, there are way les 3DSs than GBAs, and yet Pokemon X/Y has sold better. The franchise keeps growing.

From what I see so far USUM is more like the Sun/Moon Deluxe Edition as opposed to BW2 which clearly marketed as a sequel. So why bought the original when you have the complete one? It's not like you're missing something.

It's certainly possible that they're a bit undertracked, but I think that the low numbers on VGChartz are mostly due to digital sales (VGChartz doesn't track digital).

Agreed.

Really only mario kart 7 has a better digital sale ratio I bet out of the big titles.

If you want I could do that as well, I saw from Serebii Forums that the newest movie had a 60% better opening weekend than the previous one about Volcanion and Magearna. It came first in the box office and beat out Gintama, Pirates of the Carribean 4, and Cars 3.