Bro minato is a genius he can beat teen Obito from 5 to 13yeras old . But only obito ms can beat minato cause at thirteen he get trained by Madara and we dont Know Minato’s level at thirteen . Before Obito met Madara Minato at the same age would bleast him.
Kid Obito vs 4th Hokage Minato, Don't conclude Minato was fighting with a kid. Even Obito was just 14 years old, but he was an Avenger level threat. Age does not matter when it comes to war.
Thanks to Mangekyo and Hashirama cells. Imagine If Obito his 2 Mangekyo. With Hashirama cells and 2 mangekyo he would have activated his own rinnegans. Idk why he chose not to though.