>>373826994
anything above 2.80+ is a massive pain to atlas manually
you basically have to make a second UV map, lay everything out the way you want it, and tick the camera icon on the original UV map
then you make a new image of the desired size, add an image texture node to every single material, assign it your newly created image, then make sure it's the last node you clicked on. the last node you clicked on is the bake target (yes this is fucking retarded).
You should then be able to bake just fine. Note that Cycles can't bake alpha, so you'll have to bake the alpha separately as an emission map and then manually combine it in GIMP. this sucks balls.
>>373827104
only works for 2.79, the 2.80 workflow is fucked.