The 6 big franchises that can are:
Super Mario Bros.
Mario Kart
Pokemon
Call of Duty
Wii Fit
Wii Sports
GTA used to be one

Only three of those are applicable for handhelds, although, the new 3D Mario Land title's success has been encouraging; it's not really a separate franchise, but it is a sub-franchise in a different sub-genre. 3D Mario games are picking up in popularity; and level based platformers are an excellent fit on handheld systems due to the short play sessions.

OK, that needs some text.

First: Some here say, the 3DS is doing good in the US. While that's true, it's not as good as some expected, looking at the DS. The DS sold 50 million in the US and 33 million in Japan. So it was much more successful in the West. But the 3DS sells slightly better in Japan. That needs an explanation. I would've worded it different: Why does the 3DS sells better in Japan?

Second: Some claim Smartphones are the reason. I don't buy into that. That may have an impact, but that big? Remember, Japan was big into smartphones, even before the iPhone. Remeber imode-phones?

Shifting markets: The console market in Japan is shifting away from home-consoles to handehelds. That is a possible explanation, I don't know if that accounts for the whole difference, but it might explain a part of this phenomenon. So, handheld-sales in Japan increased, because people ditched their home-console for a mobile experience. That does mean, the 3DS sells not bad in the West, but it sells better in Japan.

And games: Many already said that. Japan has more games, that weren't released here (yet). We in the west also want Fire Emblem (Q1 2013, really Nintendo?), Monster Hunter and more. The 3DS has more games, that cater to the japanese audience. Look at Monster Hunter, Kid Icarus (while it may be interesting for western players, too few know about that), this japanese girl-band-game, culdcept, stuff like that.

What will happen in the future?

I think the XL has impact in Japan and the West the same. But cleverly Nintendo of Europe releases New Art Academy around the XL release. This game/application was biggest here in Europe, and it may be very cool, to paint on the big touchscreen of the XL. That will have some impact here in Europe, not too big, but relevant.

 NSMB2 naturally will be bought in West. A main Pokemon-game for the 3DS would do wonders. Pokemon Black/White 2 will have a low impact, but some will buy a 3DS for the additional download-apps for 3DS.

But the most important part will be a steady flood of normal titles (not crap, not big hits). As Japan does have this already, we need more localizations.

Smartphones aren't a hot commodity in Japan, regular phones with a lot of features are.  Why do you think the majority of phones are touch screen-less flip phones?  It's the main reason why handhelds can survive Japan.

No oniyide, as I was told the other day, we should expect games like Battlefield on handhelds now. If it doesn't make it to the 3DS it's apparently because of the lack of a default second stick, and not because they've never made a Battlefield handheld game before, thus there being nothing to suggest they ever would anyway...

@Bold. BAHAHAHA This is NintendoPie you're talking about. I've never seen a user love Nintendo as much as this guy. No, you're getting it wrong.

What he meant was, not so well in the west as compared to how other consoles usually fair in proportion to Japan, especially the 3DS' predecessor:

As you can see, it's almost 3 to 1, west to japan. Right now for 3DS, Japan beasts US and Europe individually 1 to 1.

So you see, his question is valid. For 3DS to reach the numbers DS reached, it would take for NoA to get its A in gear. Europe is another story, they're doing well with localization and such, the econonmy is just so-so I guess. But NA is still buying consoles, so something's wrong.

It is simply that there hasn't been a cross market blockbusters like Pokemon, Brain Age or Nintendogs that can push the 3DS to DS sales territory.

But beyond that, it pretty much comes down to the fact that the West (or more specifically the United States) aren't into handhelds as much as Japan. Heck, in Japan, the portable devices are pretty much King since early in the first console generation. But after little less then a year, I don't think it is valid to say it isn't doing well in one territory when the difference is about a million and as I stated, the DS at around this time had its major genre busting games being first released.

1) Pokemon is true, Brain Age too, but not Nintendogs. If you mean "Like Nintendogs", but a new IP, yeah you're right.

2) Far as I know, Nintendo's handhelds have always been big in the states (/Canada/Mexico), always higher than the sales in Japan. For the DS and Gameboy, that logic extended to Europe also:

The question is, how to explain the 3DS?

The main answers are:

• A big holiday season should be coming to start the momentum.
• Nintendo's US trends usually 1 year later than Japan trends, and higher sales usually begin in years 2 and counting, up until the trend phases back down.
• A lack of a marketing push for the 3DS in the West (imho).
• Competition from smartphones.
• A lack of compelling games to compensate for the lack of interest in the platform in the West. (like you mentioned) This should soon be fixed with NSMB2 and Animal Crossing, as well as a few others coming out in the next few months.

Needs Pokemon.

*Don't mention smart devices* *Don't mention smart devices* *Don't mention smart devices* *Don't mention smart devices* *Don't mention smart devices*

Smart devices!

DAMN!

Raw numbers don't say much on their own. There are over 700 million people in Europe, yet it's still the smallest market for videogames (of the traditional three) and always has been.