Subterranean Stalker is the fifth stage in Shadow Cosmopolis.
The battle will start with a few Pigeon de Sables. After that, nothing else will spawn until the base is hit, where Brollows and more Pigeon de Sables will be spammed, along with a Mr. Mole and Tackey.
If you take a little longer, another Mr. Mole will spawn, with more Tackeys.
Note that Slime Cat is fairly good here if you hit the base with it; the resulting shockwave will instantly kill the first Brollows and Pigeon de Sables (assuming Slime Cat is level 30 or above.)
Lineup: Crazed Macho Cat, Eraser Cat, Crazed Wall Cat, Crazed Sexy Legs Cat & Macho Legs Cat (to activate the Legs For Days Cat Combo), King Dragon Cat, Jamiera Cat, Crazed Mythical Titan Cat, Holy Valkyrie Cat, Awakened Bahamut Cat
Begin the battle by spawning a Jamiera Cat. He should be able to hold off the Pigeon de Sables. When the base is hit, the Knockback King, the Push-Back Prince himself: Mr. Mole appears, WITH Brollows, Pigeon de Sables, AND Tackeys being spammed. As quickly as you can spam meatshields, Macho Legs, Crazed Sexy Legs, and the tanks (King Dragon, Jamiera, etc.). After some time, spawn Holy Valkyrie. After she dies, send out Awakened Bahamut once Mr. Mole has finished his attack animation. Bahamut will most likely die quickly, because of Mr. Mole. The enemies should get very close to the Cat Base, so expect your base to take a couple of hits. After some time, Mr. Mole will get knocked back. Just continue spamming your units until Holy Valkyrie is available again. Try to hold out some more, and the Brollows and Pigeon de Sables will stop spawning. Because Tackey and Mr. Mole are both long ranged, and there are no close range units, the level should stop being too hard. Even if one cat enter the enemies' "blind spot", they will slowly die.
Now all that's left is to destroy the Enemy Base! Onward to Victory!
Strategy 2 (2 and 3 Star)
Lineup: Manic Eraser Cat (40), Butterfly Cat (29+1), Dancing Flasher Cat (38+2), Octopus Cat (44+1), Zamboney Cat (30), Crazed Whale Cat (30), Maglev Cat (30), Manic Jamiera Cat (30), Grandmaster Cat (25), Awakened Bahamut Cat (40)
Cat Cannon: Iron Wall, Normal or Breakerblast.
Stall the initial Pigeon De Sables with Octopus, spawn another when the first dies and use this time to upgrade your Worker Cat to a level you see fit. Once Octopus is nearing the base, spawn out everything you can as the Brollows will otherwise clip through your units and to your base, making you lose a lot of ground. Once you hit the base, spawn out everything you can except for Grandmaster and Awakened Bahamut, Grandmaster is not good against Brollows as waves make Brollows due to their attack more often, and Awakened Bahamut should be saved if the Pigeon De Sables stack up to much and you need to clear them out all at once. After that it's really just spam, not really much else to say other then that this is an endurance match more then anything, outlast the Pigeon De Sables and the Brollows and taking out Tackey and Mr. Mole will be easy as pie, try to make sure you time your units to get into the blindspot of Tackey and Mr. Mole before the Brollows and Pigeon De Sables end, but after the Pigeon De Sables and Brollows stop appearing, you no longer need to really time anything and after that, you have won the level!