Nintendo Japan has revealed 2 new Pokémon Nintendo 3DS themes: Sinister Organization - Skull Gang (敵組織～スカル団) and Alternate-colored Kapu-Kokeko (色違いのカプ・コケコ). Each theme costs 200yen. All themes are available for purchase as of March 22nd, 2017 on the Japanese Nintendo 3DS eShop store.

Sinister Organization - Skull Gang (敵組織～スカル団)

Features: Guzma artwork is shown on the top screen while Skull Gang grunt sprites and the Skull Gang logo are shown on the bottom screen.
Music: Sun and Moon OST - Battle! (Team Skull Boss) [feat. KYOtaro] (戦闘! スカル団ボス)

Alternate-colored Kapu-Kokeko (色違いのカプ・コケコ)

Features: The artwork of a Alternate-colored Kapu-Kokeko is on the top screen while Lugarugan Midday and Midnight Forms are shown on the bottom screen.
Music: Sun and Moon OST - Battle! (Tapu) (戦闘! カプ)


Source: https://www.nintendo.co.jp/hardware/3ds/theme/index.html