Here are my reasons why, he was nickname the "professor" because he imitated over 1000 ninjustus. the sharingan makes it easier to copy but i have no knowledge of whether he did the same thing. also he beat the first hokage (which madara could not) and the second hokage.
your oppinions or facts you have on this?
Correction, Hiruzen was known as the "Professor" because he knew every single technique in the village. It was never said he was able to do them. In fact, he couldn't do them. Techniques limited to their respective clans for example.
Hiruzen beat the 1st and 2nd Hokages but they were not fighting at full strength. If they were then we would have seen Hashirama use more Mokuton techniques, and Tobirama use his Time-Space Techniques.
The purpose of making Hiruzen fight Hashirama and Tobirama wasn't to overpower him. Orochimaru summoned them was more of a psychological assault. Nothing more. Orochimaru likely brought them back to weaken Hiruzen a little so he could go in for the kill himself. If I was Orochimaru, I'm sure I'd have wanted to kill my teacher with my own hands. Not through some puppets.