I'd argue strongly that is SHOULD be on both as an experiment in a Fusion style design.

The New 3DS version (and it should be New 3DS exclusive), would have limited graphical styles, AI routines etc. But be able to do local transfer of levels as well as having 3D graphics.

The Wii U version would obviously have better graphics and have more running at once. Perhaps going so far as the ability to create worlds/maps, and having more enemies and graphical style open to it.

Both versions can talk to each other, obviously when using something not in the 3DS version it becomes Wii U only.

Both versions should be able to utilise amiibos to bring in new textures, items, blocks and enemies from their respective games. Maybe even unique gameplay twists in the Wii U version (scanning Fox into a level adds a targeting reticule to shoot at enemies whilst someone else runs Mario through the level for example). So scanning in Samus would give you Super Metroid style textures, and the ability to add in some of the mainstay enemies from Metroid games and possibly the ice beam or missiles (I would argue that you would always have to play as Mario).

This has 2 effects: gives a reason for it to be N3DS exclusive (which it should be for business reasons) and gives amiibos a must own title. I think there's also a very strong argument, if it's an amiibo heavy game, for it to be a relatively cheap download rather than retail. And, in the interests of it being a Fusion experiment, it should also be crossbuy.

If it's as I've described (amiibo essential, crossbuy) I'd say no more than £15 for both versions (as the base Mario Maker doesn't need Amiibos)

This may be why the game is still in development; I think the scope may have shifted dramatically on this one.

I'd rather it be Wii U only, but I can understand why it would happen with both. However, there needs to be complete integration between both systems. When you look at premade levels, they need to be available to both the Wii U and 3DS. You can't have separate games like SSB. Nintendo needs they can work a Unified experience with games anyway. This would be a start.

Nvidia's shield tablet and the iPad air 2 beat the Wii-U in performance. An iPad mini comes close to ps3/360 and most other descent smartphones or tablets atleast put both Vita and 3DS to shame. Especially with the much lower screenresolution of the 3DS you would expect more for almost $200.

Not that these devices can compete in software or controls, but cheap mobile games that look better than a dedicated handheld game probably make a lot of people wonder what the hell is going on.

They should wait a year or two after the WiiU release. It's the one who needs the sales. After that, maybe a release on 3DS/N3DS (with a NSMB 2 bundle?).

What i meant with the Fusion strategy test, was just to see if by providing the same game on both consoles, they can actually increase - or not decrease, too - sales above their expectations.
Smash was not made for 3DS with that in mind, but if they are pursuing that path, with sales numbers and other data (like overlaping sales) they can try and see, already, if they can actually increase sales figures for their games even if they just have the same version on both consoles.