yes, but they represent other companies and systems more so than they do Nintendo. Snake has been on damn near every system out there and has a couple of Playstation exclusives; plus, MGS5 isn't coming to Nintendo. Sonic has been Mario's rival since the dawn of console gaming - the Sega/Nintendo rivalry being comparable to Sony/MS today, it's like throwing Master Chief into PSASBR. Pacman was simply ported to nearly every system ever made, I wouldn't call that "Nintendo influence." Megaman is the only one that belongs; he had his start with Nintendo and all of his games have been on Nintendo systems, many exclusive.
They're there because they're icons of gaming, not icons of Nintendo; and you say it makes more sense for them (Megaman aside) to be in a Nintendo mash-up than someone from a Nintendo exclusive being published by Nintendo themselves?
Last I checked, Bayonetta 2 is set for an October release, with no date specified; but seeing that the 3ds version of ssb is releasing on October 3rd, I somehow doubt that Bayonetta is releasing before it. But either way, Marketing works retroactively. Personally, ssb got me interested in a bunch of games that had been out for years: Metroid, Star Fox, Kid Icarus, F-Zero, etc.. Why can't ssb generate interest in a game releasing right around the same time when it can generate interest in games that have been out for years?
Okay, "influence" was a wrong term (I said it, in quotes too because I couldn't think of the right term). Presence and history is what I should have said, and even then, it still makes no sense. Bayo lacks history with Nintendo systems in comparison with the other four. How many Nintendo fans even know Bayonetta? Less of them know about her than they do Snake, who's been more on PlayStations more than anything.
Do you know how many people get addicted to Smash when it comes out? Anything with a smaller release gets shunned in favor of the bigger name. Like releasing a Rayman game the same time as Grand Theft Auto or Call of Duty. Sure, maybe it sparks interest in a select few, but everybody else will be paying attention to what's the biggest thing now.