You didn’t really ask an answerable question.
As far as favorite methods go, you likey aren’t getting answers because no one “likes” to use Unreal to make 2D stuff.
Using a 2D engine gives way better results, has less legal issues with licensing etc. So people who do it professionally wouldnt get caught dead
using unreal for it if they can at all help it.
Those who do use the engine (namely a couple of winning gamejam entires pre-covid come to mind) utilize a combination of modes/featurs however they saw fit to get their end content going.
Again, the engine is horrible at nearly everything by now, but it has always been really bad at 2d stuff.
Even a simple game like MarioBros(the first one in 8 bit) is technically impossible when done with the engine particularly if you want to hit the same memory footprint.
If you really cant look for a better engine, then use the widget system as much as possible rather than mesh planes.
The widget system allows you (at least once it did) to offset the objects with layer sorting options, which the engine is otherwise incapable of doing.
To achieve the same thing with planes you would need to physically offset them on the depth axis, which is nuts.
Backdrops for finite levels have to be done in tiling sets. Generally speaking, they handle well but at times they will sheer or glitch out while loading.
Mostly because everything you load in unreal has the lowest MIP first, and loads the full texture after. This causes scrollers to have issues when new backdrop slides load in…