This is a boss rush stage similar to Kugel Shreiber. Unlike that stage, though, every enemy here is capable of producing shockwaves. Several Pigeon de Sable will appear at the beginning. Attacking the base initiates the first wave. Two additional Pigeon de Sable will appear at the beginning of each wave.
Note: Each wave triggers after a certain amount of damage is dealt to the enemy base. This means that a high-damage cat that attacks the base may initiate multiple waves at once.
Because of the nature of the boss waves, it's a good idea to damage the base with fast attackers that have low damage. This way, the bosses will come out one-at-a-time instead of coming out all at once. This will make the stage much more manageable. Meatshields won't help here because they will be easily killed by the shockwaves. Instead, use high-health units with very few knockbacks and high damage, such as Jamiera Cat, Island Cat, and King Dragon Cat. These cats will also be able to quickly kill the Pigeons. Awakened Bahamut Cat can be useful for dealing devastating damage to the bosses, but you'll be taking a risk by using him. If he deals the finishing blow to the boss and proceeds to attack the base, he will likely trigger multiple waves to come out at once. To be safe, only use him on the last wave against the Two Can.