You are correct on Mienshao being a fighting type at least. Fast, frail— maybe so. They can be pretty quick to recover, though. Have to keep them under pressure else Regenerator might have them back up in no time.

As for the last. Correct, actually! Poison primarily, secondary of water. Your last guess is interesting because Skrelp loses the water type in favor of dragon after it evolves. [ a brief flash of a larger, 'leafier' seadragon. ] Good prediction.

So if you had to pick. Is your answer for the first one dark, psychic, or both?