To me, Tsutarja carries both traits of Ash's Treecko and the Tyrogue from Johto. For obvious reasons, the Tsutarja does not trust humans and was surprised to see humans put themselves in risk for pokemon. At the end of the episode, she doesn't even warm up to Ash. We can assume that for now Tsutarja will keep this demeanor.
Also was this attack really Grass Oath? If so, damn I hope that the other two starters learn their oath attacks so we can finally get to combination attacks.