For a limited time you can change your c-gear skin to the munna background (unless your in japan, then theres no limited time for some reason). In order to receive the skin first you need an account on pokemon.com or pokemon-gl.com
Then go to pokemon-gl.com and sign in. under your name it should have an information box. Click 'more' for it to expand and look for the part that reads 'stylize your c-gear with munna' in there it will ask for a password. the password is PGLDR34M.
Then simply go back to the homepage and click the red link that reads 'customize' and next to c-gear you should see munna