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.