>>39426569>Ninetales' entry also mentions understanding human speech but I don't think any of them have ever spoken to any humans, at least directlyOnly one did and its in the side continutiy, the Ninetails or the Ninetails legend in PMD: Red Rescue team could speak to humans in a audible voice, not telepathy. Keep in mind though that Ninetails was STUPIDLY powerful, being basically like Jevil from Deltarune in that she completely ignores the rules.
In the anime It's not possible for a Ninetails to talk to a human directly, their vocals cords preclude the possibility however they can speak to a human via telepathy and illusion and able to be quite eloquent and intelligent. The Ninetails who posed as a invented servant girl Lokoko and tried to sudduce Brock is only known example and she could speak to characters as multiple illusionary characters independently and also as Ninetails, she doesn't just understand human speech she could use it better then we could.