Yes, this is the Debug system of the game there's no menu or anything, just spawn what you want inside the stage with no restriction at all (just move the mouse over the point of the level where you want to place an object/A.I., press the number that spawns it in and **POOF**, THERE IT IS!).
'0' to spawn a Mini-Boss (with randomized costume and color)
'9' to spawn a normal enemy (with randomized costume and color) To spawn enemies inside a stage you need to use the Debug system that allows you to create them at the cursor's position anytime during the game, when you're inside a level (or even in the menu!) press:
