Guilty Gear Petit 2

The sequel Guilty Gear Petit 2 (ギルティギア プチ２ Giruti Gia Puchi Tsū) was released just eight months after the first. The game has 13 regular characters and 6 secret characters (Testament, Venom), and four "Golden" characters (GGMillia, GGKy, GGSol, and GGMay). The game was only released in Japan for the WonderSwan Color. Source: Wikipedia, "Guilty Gear Petit 2", available under the CC-BY-SA License.