He may either be Hydro, Cryo or Electro (from the elemental mats we get in his current boss). My honest thoughts, is that he is most likely Electro but with Cryo-infused attacks like Varka? Because given what we have now: Sandrone is Cryo, Capitano is Cryo, and The Tsaritsa is Cryo. We haven't gotten an Electro Harbinger yet. (Minus Childe's delusion and Scara's bait.) For his weapon of choice, it's most likely a claymore (due to his model's label) but I also want to add that, maybe also a catalyst? Like a hologram panel where he can command his needle thingies? (Idek man)

E skill would probably be like his boss's lasers or needles, both infused with Cryo but will only deal Elemental DMG if there is a Cryo character on his team. And it will depend on the characters, just like Varka's E skill. For burst, I have no idea. Just imagine it similar to Columbina's burst. Or maybe it will be something related to his segments? Like the Moon segments we see in his boss fight?

For a team (currently), I would say-   
Freeze team: Escoffier/Citlali, Furina and Columbina.   
Melt team: Citlali/Diona, Bennett/Xiangling/Lyney/Arlecchino, Xingqiu/Furina/Columbina.   
Superconduct team: Escoffier/Freminet, Flins/Fischl/Varesa, Furina/Columbina/Xingqiu/Barbara.

These are just my theories, please don't take this seriously.



My predictions for how Dottore will be playable. (Image unrelated)