It doesnt matter if he's a susanoo specialist. Madara has had the sharingan for his whole life, he wouldn't disgrace himself or the uchiha name (who are known for their powerful genjutsu) by having a mediocre genjutsu, he would obviously train to use it more proficiently.
Also, madara can cast powerful genjutsu with an eye that isnt even his own. Madara is a powerful genjutsu user as well, but this doesnt mean that he has tsukuyomi. There isnt even such a thing as a "lesser" version of it.
I can prove that I/T =/= tsukuyomi:
Tsukuyomi is a jutsu that is exclusive to Itachi, no other uchiha has been shown to possess this ability, not even sasuke (arguable).
When madara explains to obito the plan to cast I/T he goes on to demonstrate the genjutsu:
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Now look closely, you can clearly see madara using a 3-T sharingan for "this" genjutsu, now in the next scan you see madara explaining it further:
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Here you can clearly see madara explaining that he can use "this" genjutsu on the moon, thus controlling everyone ("this" genjutsu being a regular 3-T).
This proves that madara only needs a 3-T sharingan in order to perform I/T & it also proves that tsukuyomi is a completely different genjutsu (other than the name).
The juubi merely strengthens the genjutsu & makes it last forever.
Madara can't use tsukuyomi, he doesnt need it for I/T & he has never shown it.
...................................................Shisui proves you wrong...
He he he No one ever Mentioned that Shisui can't use Susano even Itachi didn't used it in any battle until his fight with Sasuke ,both Itachi and Shisui are well aware of the disadvantage of using MS tech's.................
