Milky Tunnel is the first stage in Squishy Cave.
Doge Dark will spawn as soon as the battle starts, and then respawn every 3 - 13.33 seconds
20 seconds in: Gory Black spawns, and will respawn every 10 - 22 seconds.
When the base reaches 99%: two Shadow Boxer K will spawn without a boss wave, and a delay of 3 - 6 seconds between them.
Using ranged cats such as Dragon or Sexy Legs can knockback the black enemies fairly easily, disallowing a rush. Make sure to protect your rangers with meatshields. Use any anti black units you have and area attackers since the black enemies stack up.