Flavorless? Yes. Tasteless? Not really. The closest I've found is the Isopure unflavored. It doesn't taste like anything specific, but you can taste it when mixed in to other things, if that makes sense. Its not bad or off putting, but vaguely there. I had better luck with it when mixed into savory foods (soups and purees) vs. sweet things (pudding or drinks).
Have you tried Bone Broth? Its a good source of savory Protein and hydration. You could also try the protein waters @Voogs mentioned- they are more like Gatorade; less sweet than the shakes and no chalky texture.
Isopure whey Protein Isolate comes in an unflavored variety. I've mixed with Water, milk and kool aid type drinks.
Also protein water like Premier Protein clear or Protein2O are pretty good alternatives.
