Kakashi became genin at 5, chunin at 6, jounin at 12, all that younger than Itachi. Created his own assassination move-chidori(A or S-rank technique) at the exceptional age of 12. Learned Rasengan from yondaime at a even younger age. Without being an Uchiha, he used Sharingan to the point that he was well-known over the world as a copy ninja, copying almost every technique to the point he has thousand of them, using the Sharingan so much skilfully that Itachi even admitted that his use of it is above majority of Uchihas, Obito even said he perfected the eye, managed to achieve MS, something that a self Uchiha will ever dream to possess because of his extrem rarity, and developped it to the point that it even impressed and surpass in speed and skilfulness another kamui user like Obito(main villain of the manga). He is the definition of great genius.
Minato is self explanatory since manga states he is the greatest genius that ever lived. Sorry i didn't want to break your heart concerning it U_U
