Size and power doesnt always win fights anyways. Royce Gracie proved this so many times in UFC omg. Even paper champ Rashad Evans beat Griffen.
One thing for sure though unless Andersons BJJ is better than Fedors if he went to the ground hes at a major disadvantage. Otherwise the advantage is his.
Also I highly doubt Fedor will ever come to the UFC and drop to 205 (I laugh at this comment)