Legacy m2 or current one power-up?

Since gyms in Hong Kong are competitive, power up the 96% and give it Focus Blast.

Ouch, just looking at that 69iv one is painful.

Both are worthy of a power up in my opinion. Despite the low attack stat of the Shadow Ball one, it's still going to be a good performer.

I'd probably TM the one with Ice Beam to Psychic though. Though still good, Gen 4 has introduced three new Ice attackers which surpass it significantly.

Please check the iv from your 69iv mewtwo again, this combination is not possible since the iv floor for pokemon from raids is 10/10/10

Shadow ball no doubt. There are a lot of psychic type legendaries in gen 4.

Wait and see what new raid boss we get in 12 hours. If it's Giratina, power up the one with SB. If not, wait and see if you can trade for another and get better IVs.

Do y'all think Mewtwo will keep ice beam, flame thrower, thunder bolt forever? Waiting is another option. However, I'm most interested in ice beam bc Rayquaza will come back at some point and outrage previously was somewhat difficult to battle with 3 trainers. After that maybe change it from ice beam or just flat out save and wait for whatever exclusive move/day Mewtwo gets.

Ice beam is not worth it at all, theres better ice types with mamoswine on the way, but nothing will come close to shadow ball

TM Ice Beam to Focus Blast as a gym sweeper and potential for Dialga raids or to Psychic for Machamp raids.

If that’s your only Mewtwo with Shadow Ball, power that one up. Even at low IVs, Mewtwo still has 300 base attack and will hit hard.