Board Thread:Versus Debates/@comment-36394790-20180824122210/@comment-5407586-20180830200717

Ninja Of War wrote: JOA20 wrote: We never saw Izuna using his MS, and Fugaku's is anime-only. Exactly. It wasn't shown, so how can you claim it was? The point with Fugaku was a rebuttal to the point that in the anime Shisui apparently had a Susanoo. You can't claim they didn't have the potential to awaken Susanoo because they didn't use it.

Sasuke didn't know about Susanoo because he had yet to awaken his MS. Afterwards, he learned what MS jutsu he had with little to no training. I'd say he understood the requirements for Susanoo (he's never been proven wrong about it so far).