I've read the category rules but I didn't see anything about banned emulator or specific emulator to use (if else tell me because i didn't saw it) so does it means that we can played smb3 on any emulator?

Nestopia is good to run. I don’t think there is any restriction. Just have full audio in the entire recording / stream

Emulators are allowed, but there are some restrictions. Firstly ZSNES (any version) and SNES9x 1.4x are banned. Using the runahead feature on any emulator is also not allowed.

Don't know which category you are going to run, but Any% has a few more banned emulators because they don't emulate the wrong warp accurately. These are Virtual Console, NESClassic, BizHawk (QuickNES core), RetroArch (QuickNES core). Other than that you're basically free to use any emulator.