Note: If you have good anti red/black units like Kasa Jizo or Momotaro (first evolution) this stage is considerably easier.
If you start the stage, a 400% Master A. will come out. (160,000 HP/2,228 DMG). Although the Master A is buffed, the peons aren't so strong. This is a good time to gather money. Rich Cat isn't a good choice, because it only saves time, not the actual gameplay.
IMPORTANT: Keep your firepower in check. The Master A. is NOT set as a boss, therefore can be knocked behind the Enemy Base. If you do so, a wave of the next phase's enemies will come out WITH the Master A, and that makes the stage nearly impossible. Even worse, if you hit the base hard enough, the Shy Boys and Bore will come at the same time! Always damage the Enemy Base with controlled firepower.
Also a tip: Master A has 4 Knockbacks. Counting those will help you collect money.
If you damage the Enemy Base after the Master A. is dead, an 800% buffed The Face (799,992 HP/16,000 DMG) will come out with 3 VERY STRONG Shy Boys (490,000 HP/7,000 DMG), very similar to Road of Eros or Crunchy Pillar. A strategy would be saving Bahamut and Ururun for this time. Master A. has more range than both of them, making them useless. However, the Shy Boys and Face are perfectly vulnerable to the powerful attacks of these two. You can spend all the money you like, because if all the Shy Boys and The Face die, they will instantly fill up your Wallet.
When facing the Shy Boys, spawn all that you've got no matter the cost or cooldown (Except Bahamut/Ururun/Ubers). When the Shy Boys are dead, summon Bahamut/Ururun/Ubers and maintain your line with 3 meatshields. Occasionally spawn Crazed Sexy Legs or King Dragon. When The Face is dead, instantly spawn Island Cat/Crazed Whale and 4 meatshields (3 + Crazed Brave).
After the Enemy Base is damaged again, a VERY STRONG 300% Bore will come out (1,200,000 HP/14,512 DMG). If you want to bring a status-inflicting rare cats here, use Pirate Cat, as it helps with both the previous phase and this phase, being spammable enough to contribute in eliminating the Metal Doges. However, do not use too many cats for debuffing Reds. Attackers and AOE are very important in this stage, and replacing an attacker such as Paris or Dragon with status-inflicting cats can backfire on you. If you want to bring any status-inflicting cats, make sure it helps with more than one wave.
Bahamut and Ururun will likely die from the Bore. After that, try to maintain your line. Because the money is plentiful, trusting Cat CPU is a good choice (get it from the Friday Stages). Save your Cat Cannon. When the Ubers or your Base are in danger, fire it then.
When the Bore is dead, stop anything else you're doing and continuously spawn 3 meatshields AND Crazed UFO.
After the enemy's Base is damaged again, the final wave will come out. Bun Bun Black (300%) and Director Kurosawah (100%) will appear, similar to Cave Fillet. After that, Dark Otters (100%) will spawn continuously. If Ururun is killed, don't spawn her again. Her knockback ability will cause all of your cats to fall into the range of Kurosawah and get one-hit killed. If you lack cash at any point, prioritize in sending out meatshields.
If Bun Bun Black dies, bring the Kurosawah close to your castle. Play like it's Shrimp Frontier.
If Kurosawah dies, congratulations! You've beaten one of the hardest stages in the game! Pop a champagne - you deserve it.
If you have an A. Bahamut it will help take out Director Kurosawah (Black) and the other enemies quickly. You would also need strong cats to kill Bun Bun Black (Black/Floating) if you use A. Bahamut.
The player used Pirate Cat, but some do not recommend it, and it could be replaced with Paris.