yes , i actually pulled a gadoras today from the sp crystals i got on finishing total domination. Actually i've pulled him from 2k summons before as well. Technically you can pull any unit from 2k summons (i got a lyla once , and a couple golds as well) , but the chances for anything above silver are really low. Even the chances for silvers are not that great (3% if i remember corectly)
Actually , dunno what to suggest about your nanaly issue. Personally , i wouldn't cr black units. They are really damn strong on their own , and 1 cr ain't gonna make 1 much better then having 2. Having 2 nanaly will shred pretty much anything that isn;t seriously armored. Add a dancer on them and SAW both , and you have insane dps... Actually , when second awakening comes , i believe that all blacks can chose between 2 different routes with different art and bonuses. You might want to keep both for that.
And if you're one of those guys that dislike doubles , well , there is always the option of discharging them for rainbow crystals. In the future , we;re going to get some pretty good units (even now , the black knight is pretty strong if you have the money to trow at him)