Young Prodigy...
1. Kakashi himself has been referred to as a prodigy. He graduated from the Academy in a single year at the top of his class at age 5, eventually joining a team under Minato Namikaze alongside Obito Uchiha and Rin Nohara. A year later, Kakashi became chūnin after facing and defeating Might Guy during the third stage of the Chūnin Exams.
2. Itachi was a highly perceptive child, wise beyond his years, he was praised by all as the best of his generation, and a genius above all others. At age 7, Itachi graduated from the Academy at the top of his class after only one year,[11][5] mastered the Sharingan at age 8,[11] passed the Chūnin Exams at age 10,[11] enrolled in ANBU half a year later[12] and became captain by 13.
3. According to those who knew him personally, Minato was a very talented ninja prodigy — a rare genius that appeared only once in a generation.[5] He graduated from the Academy at the age of ten,[1] and was added to a genin team under Jiraiya,
4. Nagato activated his Rinnegan when he was a child and were able to kill 2 adult shinobi. He is also gifted alright.
5. From the latest manga, Madara and Hashirama looks like 13 cause they look a bit older than Naruto and Sasuke when they were 12 y/o. We'll see in the next chapter their ability as a child. Hashirama did show some mokuton ability on chapter 622 and Madara already has an activated sharingan chapter 623 and can kill Adult Senju so they are classified as gifted/geniuses also.
6. Orochimaru stood out as a genius — his talents, knowledge, and determination were considered by Hiruzen to be that of a prodigy seen once in a generation. His picture as a child seem a bit older than Madara and Hashirama. So may be he's around 13 or 14 when he was recognize.