I will teach u how to beat it but u must read and follow all the steps:This stage is radically different than the others, featuring a powerful and fast attacking enemy as boss. For this reason learning to meatshield is mandatory, and so is getting at least the most important treasures. Any uber you have by now, if you have any, is likely to help, while units like Titan Cat or Island will be a waste of money.
Strategy 1 Edit
First of all, all of your cats have to be at level 20. Make sure you have acquired lots of gold treasures from previous chapters or else you'll never beat this stage. If you have him, Shaman Cat makes keeping Bun Bun in place easier.
Lineup: Macho Cat, Wall Cat, Sexy Legs Cat, UFO Cat, Dragon Cat,and True Valkyrie Cat (other cats are optional). If you have any anti floating cats, use them on this stage.
When the battle starts, spam Wall Cat, and Dragon Cat. Meanwhile, upgrade your Cat Wallet. Once Sir Seal will be close by, spam Dragon Cat. By the time Mooth comes, your Cat Wallet should be already maxed out. Just keep sending out the same units. Once your money has reached its maximum capacity, send out Valkyrie Cat. This way you will slowly proceed toward the enemy's base. You should be able to spawn another Valkyrie Cat once you start hitting their base. After that start spamming meatshields and Dragon Cats. Once Teacher Bun Bun spawns, your 2 Valkyrie Cats will most likely die. Keep spamming those same units, but this time add Sexy Legs Cats. But you always want to have at least 4000 money, because you want to spawn Valkyrie Cat as soon as possible. Yet thanks to all of those Mooths, you should have enough money. When Bun Bun is near to death, start spamming UFO Cats. A good option is to stall Teacher Bun Bun at his base to allow time for him when he passes through your pushes.
Finally, once Teacher Bun Bun is defeated, you can head to the base and claim victory.