Gundogan has recovered from a dislocated kneecap sustained towards the end of his time at Borussia Dortmund.
Guardiola revealed the German will be a key man in their midfield this season.
"Ilkay is a player that when he is fit, he is quick with the ball, he can pass with one or two touches, he is so intelligent," he said.
"He is an attacking central defender or midfielder on the ball, he can arrive in the second line in the box.
"He has a lot of personality. With penalties, he can shoot. He had a lot of injuries in the past."