"When has Nintendo ever done this?"

That's the whole point! Nintendo never releases a new game for 2 different platforms! That's why I always also need a handheld. Otherwise I could not play Mario 3D land or Mariokart 7, to give 2 examples. If there ever will be a Luigi's mansion on the Wii u, it will probably be Luigi's mansion 3!

If this rumor is true that would suck because the Wii U version would easily out shine the 3ds version. I really hope this is just a rumor because this is one of the 3ds games I am really excited about and it would be a shame for a game with so much potential to go to waste.

It would be a bit odd.

I'm still finding the connectivity between 3DS and Wii U Smash Bros. hard to understand. I'm getting it on Wii U but do I need it on 3DS too? It can't be the same game right?

Luigi's Mansion 2 on 3DS couldn't possibly be the same game if it were to be on Wii U as well....
Having 2 versions of the same game only to have one of them being more technologically superior to the other?
Nintendo would be shooting themselves in the foot.

I can understand Smash Bros on 2 systems because it is one of those type of sereis that, like mario kart can handle it. I dont think Luigi's Mansion though is one of those games. One is bound to over sell the other.

@GamecubeMan32. I agree. They could easily have the 2 Super Smash Bros. games vary slightly, either by characters, stages, or whatever. Either way, its Super Smash Bros. on a handheld, I'll be getting it on Wii U and 3DS regardless

If Luigi's mansion 2 would come to the Wii u, then the 3DS version may be canceled. That may be a possibility, since it has gone pretty silent on the title. But for that reason the same could happen to Paper Mario 3D (though not very likely).

This would be a first for Nintendo, wouldn't it? It would be risky since a large amount of people who plan on buying the Wii U also own a 3DS and deciding between them would detract sales from both. If they did this I'd rather see them take a page from Epic Mickey 2. Both coming out at the same time but being completely different games.

That would be a bad idea, especially if each version had exclusive content.
There's no way I'd be getting two copies and I don't want to have to choose between a 3DS and Wii U version.
I'd love a Luigi's Mansion on the Wii U... But it has to be a completely different game to the 3DS game.
Good thing that this is most likely not true at all.

I fail to see the connection if they are different games. They're both not "Epic Mickey 2"

Here's my theory
So Luigi's Mansion 2 was supposed to be released at Q1 (believe it or not) nothing else was announced about this game since E3, almost like how their keeping the Wii u on the DL. As well with every other game announced, so it would make sense if Luigi's Mansion was apart of this clan. Therefore I would guess Luigi's Mansion 2 will be delayed until the Wii u launch.
Why make 1 game for 2 consoles? I believe the Wii u will have the power to stream their games to the 3DS, and Vice Versa.
After all Nintendo is developing 2 versions of Lego City Stories, and publishing 2 versions of Super Smash Bros 4.

Wut?

Actually, Nintendo is only publishing Lego City Stories.

Lemme simplify it for your bird brain. With point form reasons Luigi's Mansion might go on Wii u.
1. No news was released about this since E3 (becides the announcement of no multiplayer) meaning we haven't been updated of anything they have done post E3.
2. Nintendo developing Lego City Stories, and Publishing Super Smash Bros 4 for 3DS and Wii u.
The reason they might make 2 versions could be because the Wii u may have the feature to play 3DS games (Similar to the relation with the PS3 and the PS Vita)

^So by your theory, I will be able to play some HD Zelda game in my 3ds. Really? What was said is that you may be able to control some Wii U games with your 3ds, playing them would be impossible. And yeah, you can't actually play Vita games on your Playstation 3.

No, this feature would only work for certain games, (if true) and this would port the graphics, similar to how it's done on the Zelda Wii u tech demo where with the press of a button, you can put your HD Zelda game on the tablet by lowering the graphics, because the tablet cannot handle HD and I got it confused, the Vita can play PS3 games (not all of them, of course)