The Naruto Shippuden Comics world features several enemy types.
It’s always fun to look at the enemy lineup first in any world, and work backwards to the characters that oppose or confront them.
The enemies often tell you more about the construction and alignment of the world than the heroes will.
Enemies are often baked or evolved by their world surroundings – literally made out of the stuff of the world: lava, shards, parts, effluvia, bio-organics, etc.
If you look at Mega-Man, Pokemon, Magic, you’ll see these similarities.
Sometimes there is a pattern to how these enemies evolve and what we come to expect from them based on the pattern. Some borrow heavily from a world theme: machine/human, insectoid, supernatural, powers based, and so forth.
Whatever their origin though, they help setup the world boundaries (edges of evil) and suggest the best sorts of interaction with the hero characters.
A great resource for thinking about character construction is Barlowe’s Guide to Extra-Terrestrials – the perfect construction reference. It isn’t just useful for extra-terrestrials either. There’s plenty to learn from how Barlowe sets up character properties for illustration.