I have searched the web enough and from what I have found (posts from years ago) this wasn’t possible (no anti-aliasing and no texture alpha transparency). My tests today still lack both. Is this still true or is there a trick?
I have a tree which I would like to bake to a plane to make billboards but that’s not possible without the alpha from the leaf textures.
I think it’s still true. You can bake the alpha and then apply it to the color.
You can also render your texture at higher resolution and let the anti-aliasing append when rendering (if you re-render with cycles or other) . Or just render higher and scale down the image to let the scaling redo the anti-aliasing.