There’s quite a bit of misinformation in TheJamsh’s posts.
The process for becoming a developer for Nintendo is no different than the one for Sony or Microsoft. And they have been catering to indie users, quite a bit, actually. They constantly feature indie games in their online stores and you get a “free” Unity license when you join their Wii U indie development program.
The Wii U, however, is technically more like the PS3 and 360 than the PS4 and Xbox One, which is the baseline Epic decided to support on consoles (it’s also the platforms their AAA customers demand the most), so they implement platform layers for both by themselves. But as long as you can get your hands on a Wii U dev kit, nothing stops you from making a port yourself. Actually, this is being done by Armature, who are tasked with porting Bloodstained for the Wii U as a Kickstarter stretch goal. However, the game is slated for 2017, when the Wii U’s successor is likely to be released.
As for the 3DS, its tech specs (dual 266MHz ARM11, 128MBs of RAM, of which only 64MBs are usable by the games) are way below the required to run UE4 and even Unity (but I know of a few developers with source access to Unity who actually did their own 3DS ports for a few simple games, but it’s not on the level for general usage). The New 3DS does improve things quite a bit (quad 800MHz CPU, 256MBs of RAM, 170MBs usable by games), but it’s GPU would be a challenge to work with on UE4 and it’s a stop gap for Nintendo’s next platform, porting UE4 for it would come out too late. Nintendo and Unity even announced Unity support for the New3DS and it’s still not released, for example.
Nintendo’s next platform(s) is probably a different story. Rumors hint at their next console having some sort of parity with the PS4 and their next handheld is very likely to use hardware derived from modern smartphones. Square Enix’s Dragon Quest XI, which is done with UE4, was announced as also being on Nintendo’s next console, so it hints they might be planning on securing UE4 support (the Wii U benefited a lot by having Unity support - ports of indie Unity games make up the majority of releases in their digital storefront, so they probably realized the advantages of having popular middleware running on their platforms).