Wrigley was trained indoors. We have a litter box downstairs, but we use pads not litter. We didn't go with litter because we were afraid that she might eat it and the mess of it.
She does both in the same spot, but she has been known to remove poo herself if you don't get to it quick enough!
We use a pad upstairs or if we go away and she uses that just fine as well, she NEVER has accidents!
She was the easiest to train, but her breeder already had her going on pads, so obviously that helped!
Crosley goes outside and so does Camden. If we are outside, Wrigley goes out there too and there is never any confusion with her!