I have a friend saying that Itachi can solo MS Obito with finger genjutsu and his other techniques without even having to use tsukuyomi which I find ridiculous 
Exactly this^^Naw obito is a uchiha with ms an rennigan aitn no regular finger genjutsu is working on him
Pretty much. Itachi has the best feats with genjutsu and was the best user.In terms of genjutsu its pretty much definitive that Itachi will win against obito
-Sharingan genjustu on clan members isn't completely pointless. Sasuke took a few moments to see through Itachi's genjutsu during their fight. Also, clan members fought against each other for years, using Izanagi and Izanami.Exactly this^^
You can't use a sharingan genjustu on a fellow clan member it is completely pointless.
Tsukyomi by uchiha blood is an automatic counter.
The finger genjustu isn't a sharingan genjustu, but a regular one.
That can easily be waivered by distrupting your chakra.
The ms Obito that controlled the kyuubi and a perfect jinchuuriki isn't going to falter to any of Itachi's genjustu tricks.
Especially when it failed against 3 tomoe Sasuke...
People need to realize there is a reason why itachi didn't go after Obito with his current genjustu level.
-Using inzanagi or inzanami wouldn't be wise, considering his ability to use Uchiha kinjustu himself.-Sharingan genjustu on clan members isn't completely pointless. Sasuke took a few moments to see through Itachi's genjutsu during their fight. Also, clan members fought against each other for years, using Izanagi and Izanami.
-It is a little hard to break Tsukiyomi though, considering that one only has one second if Itachi decides to make it last that long. When Sasuke broke it, it seemed that Itachi prolonged it in order to give him a chance to do so, considering that Zetsu even took time to notice it, meaning it occured longer than 1 sec in real time.
-MS Obito isn't getting hurt by finger genjutsu. That is true.
-That argument can honestly go both ways. Itachi has the excuse of barely being in Obito's presence, considering that the Akatsuki did not meet altogether for the first 4 years he was a member and he was paired with Kisame...meaning he saw very little of Obito. Also, I doubt that Obito would stick around if Itachi went after him and Zetsu did keep watch for Obito, he would know if Itachi were coming for him or not.
-It doesn't quite make sense on the other hand that Obito kept Itachi around. If he could have killed him, he would have. Obito was the only member who knew the truth about Itachi...meaning that he knew Itachi would never capture Naruto. Itachi didn't even help the other members capture their tailed beasts, he just helped with sealing which pretty much any other missing-nin could do. If Obito were capable of killing Itachi at the time or thought he could have, he would and just replace him with a missing-nin who would be more than happy to actually be for Akatsuki and capture Naruto. That and if he did that, his plans wouldn't have to be on pause for 7 years.