There are several kind of enemies. They are all different.
For instance, turtles can kill other enemies, spikys can't be jumped upon, cannons are extremely hard.
Cannons are a good hint of being playing in higher levels of difficulty.
And turtles and goombas can be winged, being harder to face.
Should we implement the enemies as different states in the automaton (#16)? Or just one state, and in it pick by a different criteria, or randomly (bad idea) which enemy to place?
Reflect upon this and decide.