As much as I'd love Conker I don't see him happening. Aside from the fact that his game didn't release in Japan, it'd be very hard to implement him faithfully without increasing the game's age rating between the guns, booze and urine....
Conker
could be implemented into Smash a-okay. The thing is, in-game, there are two levels where you get drunk and urinate. Both sections are very brief. Just like Conker's swearing, it's used sparingly throughout BFD. It's funny, Conker is one of the most PG characters in his own game.
Another thing, all of Conker's weapons are kid friendly. Even if you took away his guns, he can still have a very creative moveset with his Context Sensitive ability, chainsaw, tnt, slingshot, knives, crossbow the list goes on. If you take the liquor away from the squirrel it wouldn't be a problem because outside of cutscenes and brief gameplay, alcohol isn't a very important aspect of BFD. Conker was able to appear in Project Spark without needing to swear or drink, so I think he'd qualify for Smash. And if there's one more thing for me to add:
Bayonetta: Blood and Gore, Intense Violence, Partial Nudity, Strong Language, Suggestive Themes
Conker: Animated Violence, Mature Sexual Themes, Strong Language
I'd say Nintendo already took more of a risk adding Bayonetta, who's attire alone and history of making enemies explode into bloody chunks is already risky enough. A friendly looking cartoon squirrel (with white gloves to boot!) with a ton of different weapons isn't necessarily out of the question.
Until Sakurai comes out and says he's biased for games that were released in Japan, I'm going to continue supporting the squirrel. Even if he did come out and say that, I'm going to continue supporting the squirrel lol.