There are themes for Motorola, but it's embedded in the firmware; unless if you flash your phone's software with a third-party ROM hack (which is risky and can void your phone's warranty; I once flashed a T-mobile-spec Moto V360, hoping that I would unlock it, but I ended up bricking it), you can't make your own themes in a V360.
And what software do you use for making one? If you're making a Nokia theme, you can use the official tools available from forum.nokia.com, although you need to get used to the interface...