Hell on 3 Wheels (Expert) is the first stage in Tricycle Awakens!.
There will be only one Unicycle Cat, so don't be too alarmed.
A good way to beat this stage is to spam meatshields (Macho Cat, Wall Cat, etc.) and spawn a Crazed Bahamut Cat (at least 15 or above). Keep spamming until the Unicycle Cat is beaten. If you have any Uber Rare Cats or other high-damage cats that can attack the enemies, use them as well.
If you don't have Awakened Bahamut, then he may be substituted for another rusher like Yukimura, though this is untested. All you need to is spawn four to five meatshields, a stream of Paris Cats (True form is even better) and Awakened Bahamut when you have enough money. He should kill the Unicycle Cat after three to four hits.