Yeah I didn't want to say anything considering the thread we had praising Crafted World for how good it looked despite it's resolution, but, with UE4 games it seems like you always have to give something up in comparison to a Nintendo in-house engine. It would probably have better framerate or resolution if it was EAD. 

I have to admit, I couldn't really remember if the game was 60fps or 30fps and I just assumed it must be 30fps (because of Kirby Star Allies ironically, lol)! 

It is definitely one of the best looking games on Switch, but I do have to wonder if using a Nintendo engine would have made it much smoother. Not just in resolution, but also in development time. Yoshi, as a fairly standard 2D platformer with a somewhat quirky concept, really shouldn't have needed a year-long delay. 

Again though, I think it probably makes sense to use UE4 when it's a third party developer making a Nintendo title. I'm not sure why they don't use Nintendo engines because you'd think Nintendo would supply them with everything they need such as engine experts, and I imagine there are fairly regular checks on third party devs to make sure they're making their games properly (MP4 being an example). Maybe it just makes more sense to use one of the better third party engines and not to hog resources from Nintendo, as I imagine the studios can do the majority of the work themselves if they aren't use a proprietary engine they might have less experience with.

Unreal Engine is kind of garbage, so...ideally no. At least not for anything that demands high framerate/graphical fidelity.

Not well informed enough about Unity to say for it.

Yeah that's why I said that it needed an improvement in resolution. It actually is pretty detailed aside from that but the resolution suffers. 

Yoshi is a great game to play with the little ones via coop. If anything it is an example of why resolution is overrated, given yoshi looks great.

I game on a 65 inch tv and had digital foundry never ran an in depth analysis, I would have never known it had resolution "issues." 

Art style matters, not pixel count.

Unreal is very capable.   Dragon Ball FighterZ is UE4 (and works wonderfully on Switch too), Dragon Quest XI is as well.  So is Kingdom Hearts III.  And a number of other games.

Well, don't forget Woolly World had the same development struggles and it used a bespoke engine rather than a third party one.  Good Feel just aren't fast devs.

It really depends on how mature the in-house tools are for a set game. For certain titles and genres, Nintendo have some specific needs that would probably be better suited to the custom tools that they've already developed in-house. The whole point of third-party engines is that a lot of functionality is in-place so you don't have to play around with it as much. If they already have that functionality in-house then there is no need use UE4 or Unity, in-fact they could be a hindrance if you have to make extra modifications for a specific game. For a new game/genre that's completely fresh, then a third-party engine could help speed up development.

Take Bioware as an example of a developer using a third-party (OK, not entirely third-party, but not developed in-house at Bioware) engine that's not appropriate to their needs. Their last few games have taken forever to develop and have been sub-par by their standards. A lot of that is because they used the Battlefield engine and had to do a load of custom work to make it suitable for their RPGs.

Unreal Engine 4 is awful on home consoles but I imagine it works better on Switch's hardware setup and for Nintendo's case as well so why not ?

I don't know one single game which uses UE4 and runs in 60fps or even stabile 30fps on Switch. Abzu, Snake Pass, Octopath Traveler had bad and countless framerate droppings, Rime was almost unplayable. So.... no. If Nintendo don't get their Yoshi game run in constant 60fps at 576p, I think it's almost impossible to use this engine properly on Switch.

Digital Foundry suggested the Link's Awakening remake may have been made in Unreal Engine 4. I think Grezzo did advertise for staff with Unreal experience back in late 2017, when they were likely recruiting for the Link's Awakening game. Link's Awakening looks gorgeous, but one issue every preview mentioned was frame-rate drops in the game's overworld, which fits with other UE4 games on Switch.