this may be copium, cuz i dont want to have a bipedal evo again for the water starter, but my theory is we get a water/ poison komodo dragon. They are indigenous to islands in komodo, and with the purple eyes, I have a vague feeling we are getting a poison type, which would be perfect for the other dragon. I was also looking it up for anything toxic/poison related to Indonesia to see if anything could be added to this motif, and there is. Apparently, due to artisanal and gold mining, Indonesia , correct me if im wrong here, is a significant contributor to mercury pollution, a toxic metal liquid. And from what i checked up, a symptom of mercury poisoning is hypersalivation. Komodo dragons drool all the time!
imagine it, a water/poison komodo dragon, that spits out and drools silvery mercury to poison its opponents.
now, I do understand this could be a controversial design, so gamefreak may not go with it, but I at least think its a plausible one
by Cheap_Gap1446