It has been confirmed that Garrus can be party member. But Legion he is still has not been confirmed. Though there are a few achievements that suggest you can get legion as a squad member.
Yes, it is confirmed because I did it myself, you can get Legion as a party member.
In Mass Effect 2? Well Garrus is practically mandatory but with Legion you can choose if it its your squadmate or not. In Mass Effect 3? If they both survive the Suicide Mission... we know Garrus will be a permanent squadmate, Legion could be a temporary squadmate or will just "be there" when you need him (as we saw on the Reaper's Base Trailer). --StrikerXE 01:09, July 21, 2011 (UTC)
^^^ Achievements? For ME3? Where'd you see that? I'm curious. ^ I think he means achievements for Mass Effect 2. If not, I'm curious as well
Legion is not a squad member in mass effect 3 as of yet