With the refurbishing that SAA have passed, Rao became a Wildcard trooper. So, can he link in a Fireteam core of Regulars with already 2 Bagh Mari in it?
Yes, because he's a Wildcard for Fireteam composition, not a Bagh Mari. If he was a Bagh Mari for Fireteam composition, he would be labeled as such.
See any wildcard trooper as a joker. Or a changeling. He is any troop you need him to be in regard of the FT creation.