for all of you saying that tobi doesnt have ms u are all idiots u need ms in order to get rinnagon tobi is an uchiha i said it so many times before go read the manga again think before u pozt
Tobi transplants the rinnegan eye. We aren't sure he started with it. According to him, he says he gave Nagato the rinnegan, but there is no way you can trust him or not. We should assume he has the MS because of how he has the Eye of the Moon Plan, which he needs Tsukuyomi to do. And for Tsukuyomi you need to get MS. But that's assuming. He might not know Amaterasu, therefore he cannot get Susanoo, according to the 3rd Databook.
I think he should have Susanoo, but maybe he didn't want to show Konan that just in case she comes back to life by unknown means. Or if Konan survived. He might want to surprise people.