Littering Coast is the fifth stage in Sub-chapter 26, Sea Polluter.
A challenging and banterous stage. At the start, an incredibly magnified Wall Doge will spawn. Groups of three Assassin Bears will spawn in one-minute intervals throughout the battle. DO NOT fire the Cat Cannon unless you're killing the Bears, and make sure that all three are on-screen to ensure they're taken out by the cannon.
If you have all the Energy Cores 100%, this stage is not completely challenging.
Use cheap meatshields that can near-eternally stall the Wall Doge. A constant stall of Crazed Cat and Mohawk Cat can hold it in place. Then, either stack up cheap ranged damagers like Macho Legs and Crazed Sexy Legs or high DPS units like Awakened Bahamut or Balrog to dish out damage to the boss.
Metal Cat is very useful on this stage, not only for holding off the Wall Doge, but also for briefly stalling the Assassin Bears until all three are on-screen so the cannon can eliminate them.