Toon, how are you making your toons?
However you’re making them. Render them out with an alpha channel of the character. Which means your character has a fully white solid shape of their animation. To use as amask.
Put them on a CARD in unreal or a flat plane with uvs on it.
https://forums.unrealengine.com/deve…channel-to-ue4
So hopefully you can spit out your 2d animation as an image sequence, a PNG sequence, or something that supports alpha channels. Place that in the midst of your scene… see if you can get that going from there.
You ever checkout GREASE PENCIL from blender? Might be a cool tool for you as well.
This is assuming a character is just say, walking down a hallway. You do a walk cycle, and are moving the camera toward them. Complex animations with the camera is going to require you blocking out the animation with an animated camera first to match perspective, and all that jazz.
The method im talking about is jus tputting out a pre-animated thing on a card with a mask around it. So that the background of the character is transparent.