It is recommended to use at least 4 meatshields. You can also use Dragon/Crazed Dragon, Macho Legs and 3-4 main attackers - special cats like Ururun, Bahamut, Holy Valkyrie, Li'l Nyandam and Mina or ubers if you have.
Stall the Duches and save money for the attackers. Also, you might need to spam your cats quickly, so you can use Cat CPU too. It might take a few tries to do it right.
It was previously written that this stage can be infinitely stalled if enemies are synced, however this is not true due to the fact Duche and R.Ost are both Area atk.
This stage can be greatly simplified if you have Diabolic Gao, as - despite the name - both the Duches and R. Osts are traitless enemies and therefore take triple damage from D. Gao.
The Jumpon1 (o3o) method (2/3 star approved):
Your spicy first row: Macho cat, M. Macho cat, Eraser cat (has to tank 2 r.ost hits) M. Eraser cat(Lv 40 NEEDED), Thaumaturge cat (da spicy boi) Second line: Dual Legs and Dragons (Lv 30 min for crazed/manic forms, +40 for Normal), Strong hitter (Tecoluga is a cheat code for this stage) or Uruan/Bahamut (normal and evolved only) Items: CPU(makes everything easier to spam), Rich cat(Use on 3 star, not needed on 2 star but helps), Sniper (Will be explained), Speed up (ONLY if you dont wanna spend time)
The plan: Unfortunately, this stage is hard to stall at the start in 3 star (2 star is easier but annoying) and requires you to get ready immediatly. Start by spawning your heavy hitter/special hitter and 2 dragons, don't spawn legs yet. Once you kill the duches, spawn legs and dragons and turn on cpu AFTER the first R.ost arrives at your meatsheilds. This is where sniper kicks in, it will allow your ranged stacks to attack a target at a time, knocking back 1/4 R.osts and stopping the push, also allows your heavy attack to get in hits. While this strat requires strong cats, and a few boosted ubers in 3 stars, makes the stage easier.