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.