[Brainchild]

I don't know about Alata and Eri being siblings. I think childhood friends works out a little better considering that Agri and Moune's personalities were pretty much "look guys I have a sibling on the same team and we're both very strong", so they'd either require major retooling or they'd have to be kept siblings. Frankly, I think the most workable character, beyond Alata's generic red ranger, would be Hyde, as he's just the typical older wise guy. Gosei Green didn't seem to be too important to him in the long run.
As for good old Datas, I'm guessing they'll go with the Alpha personality. Their movements were actually pretty similar if you think about it, with the whole arm flapping thing that Datas had when he was running.