TM Mewtwo or not?
I'm fortunate enough to have 3 Mewtwos -- 2 with Shadow Ball and 1 with Hyper Beam. Would you TM the third one to get Shadow Ball before the move change or keep HB because it is also legacy and there is always the chance of a shakeup that could make it relevant?
I have other options for Psychic bosses, including 3 maxed legacy Gengars and multiple powered up TTars with Dark movesets.
UPDATE: Thanks, fellow trainers, for the input. I decided to TM my third Mewtwo (and it only took 2 CTMs!). Although I hate giving up a legacy mon, I didn't want to miss out on having a third, relevant mon for raid teams.
Answers
Why do you need to spend all those TM's on nine mewtwos? Seriously..
As for the OP, i would keep Hyper Beam for legacy purposes. I TM'ed it onto my worst Mewtwo (a traded one that has less than 66% IVs, which i will never power up.) legacy pokemon are collectors items.
Hyper Beam will never have any offensive potential on Mewtwo no matter what.
Yes, you are of course correct, and I typed that without pausing to think about it. My bad. Ghost is a rare and fragile type among gym defenders, whereas normal is a very common and bulky type seen in gyms, so I'd still argue that HB is Mewtwo's only true generalist charge move, but my comment about HB not being double resisted was dead wrong.
I think it is a tough call for you to make. You have only 3 Mewtwos. Shadow Ball is the best and Hyper Beam the worst of the four charge moves. But it might be nice to have a Hyper Beam Mewtwo, just in case, or just to have one of each. I have 15 Mewtwos, so I TM'ed all I could to Shadow Ball until I ran out of charged TMs, but I was careful to leave one Hyper Beam. I ended up with 8 Shadow Balls. I do have the one Hyper Beam, and that was because I had a whole squad (6) of Shadow Balls. In your particular case, and if I were you, I would try to TM all 3 to Shadow Ball. In my TMing, the moment I hit 6 Shadow Balls, I was careful to preserve a Hyper Beam after that. Its just really a question of performance versus completeness. A hard judgment call. Just go with what you want.