Instructions
Look at the color of the front of the head. It should have sparkle to it when you look closely. Some of the fake Bakugan have a darker color than the real thing and no sparkle.
Inspect the tail. It should be gold. A fake Bakugan might have a tail that is the same blue as the rest of the body.
View the number on the top of the head. A real Bakugan has a squat font, while a fake might have a tall font.
Look at the back of the packaging. It should have the Sega or Spin Master logo on it.
Inspect the quality of the cards you get with the Bakugan. They should have a nice look to them, with bright colors and sharp drawings.
Inspect the screw in the center of the Bakugan. Real ones will have a triangle screw, while fakes will have an "X."
View inside the Bakugan to see a copyright symbol. It should read "S/S/B," and nothing else. A serial code will be on the bottom of the new versions.