What's interesting about the Gematsu lists is that, besides the third party characters, there seems to be a reoccuring theme of the characters mentioned: they're all, in a way, much more contemporary additions, basically representing modern Nintendo. (Wii, DS, 3DS)
Mii and Wii Fit Trainer are pretty obvious in this regard. They represent Nintendo finally being back on top of the console market after years of middling to poor hardware. Animal Crossing started life back on the 64, but got way more popular on the DS and 3DS.
Xenoblade and Rhythm Heaven are a bit more niche, but they still have some sort of notability behind them, as far as new Nintendo series go. Xenoblade had the Operation Rainfall buzz behind it, Monolift is a first party dev and I believe they did have Nintendo help develop Xenoblade with them, XB was critically acclaimed and gained a lot of attention, the game is getting some sort of sequel/spiritual successor, etc. Rhythm Heaven has the weight of Yoshio Sakamoto and Nintendo SPD (Metroid, WarioWare) behind it, and has three games and apparently sells relatively well. In comparison to series like Sin & Punishment, Chibi-Robo!, Captain Rainbow, it seems like there's enough merit to give XB and RH some playable representation.
Little Mac and Palutena aren't exactly "new", but it's because of Punch Out!! on Wii and Kid Icarus Uprising reviving their respective series that put them in the position they are today. Obviously, if it weren't for Uprising developing Palutena into the character we know today, she wouldn't of had support. Let's be honest: The same could of been said for Little Mac. I know he had more support than Palutena did back in the Brawl days, but it wasn't until PO!! Wii that really distinguished him from the rest of the other NES characters that didn't (and probably won't ever) get in, like Mach Rider, Balloon Fighter, etc. Had it not been for PO!! Wii, I'm certain Little Mac would of most likely just returned as an assist trophy, like how if it weren't for Uprising, Palutena would of probably just remained in Pit's FS.
Greninja is obvious as well, of course, originating from the most recent Pokemon games and seemingly gaining a lot of popularity. One thing that made people skeptical of this list is how he never mentioned Rosalina....but to be honest, her inclusion also supports the notion of this game's additions being more 'contemporary'. She's basically the big new Mario character that Nintendo seems to be pushing, and it also helps she represents the Super Mario Galaxy games, the most important and critically acclaimed titles in the series since Mario 64 back in 1996. Then you have Chrom, the protagonist of the most recent and successful/popular Fire Emblem game on 3DS.
So now we're just left with Mega Man and Pac-Man. Now, MM has unfortunately appears to have been pushed out of the spotlight by Capcom, but Namco has been giving the Pac a bit of a push lately, what with the new design, games, and Cartoon, so he sort of falls into the 'recent' category as well.
All the characters above have had an installment on either Wii, DS, and/or 3DS. Unfortunately, I feel like this harms the chances of someone like King K. Rool, considering he hasn't been the villain of any recent DK game in quite some time (It could, however, help Dixie, because of her recent role in Tropical Freeze).
