True, but I honestly can't imagine the red-eyed kid relying on a Chansey, if it's his, which we still don't know if it is. While Ash may see the best in all Pokémon, most villains typically go for the strongest (i.e. Mewtwo, Genesect, etc.). The red-eyed kid could be an exception, I guess, but I'd rather theorize under the assumption that he is not.
As for the TM, not necessarily. We're not sure how TMs are applied to a Pokémon, but it's likely that a Trainer isn't required. In the Pokémon world, people drop random stuff on the ground all the time; it's not a stretch to say the Chansey found the TM after someone – perhaps Norman, since Mr. Briney lives kinda close to Petalburg City – dropped it.