The battle starts with one Hippoe. After around 10 seconds a lione Hippoe will spawn. The Lione Hippoe will spawn during the entire battle as peons with also Hippoes. The spawn rate is random (mine where between 1 and 30 seconds) After around 20 seconds Sister Lione will spawn with a few peons.
If you want to beat this level you will need 3-4 meatshields. Cats that can freeze Sister Lione are also higly recommend. If you have cats that outrange Sister lione then bring them. Do not bring ubers who can easily get hit by her as they can die easy.
Strategy 1 (Not tested)
Row 1: Macho Cat, Wall Cat, Kotatsu Cat, Dragon Cat, Mythical Titan cat
Row 2: Sexy Legs cat, rest is yours to fill
Kill the Hippoe and Lione Hippoe for a cash boost, Sexy Legs and Dragon should do the trick. Once Sister Lione comes out, start using kotatsu (higher the level the better), be sure to spam dragon. Send when you can, and you should be able to ace it.