Should i power up my Mewtwo?

I got a 10/10/11 Mewtwo, so my choice was easier, but I'd say you should do the same and not power it up.

Rare candies are super valuable. While Mewtwo is rare, it's always possible to do another raid (unlike say, kyogre who just left us and probably won't be around again for at least 6 months if not more). I'd ideally want a 90+ iv Mewtwo, but even 82+ (i.e. average) is acceptable to power up. Anything below average? You've got a good chance at getting a better one next time, so prioritize ex eligible gyms every day and try to get another invite.

Regis are terrible anyways, so you can skip a t5 raid to do an ex eligible instead, try to hit 4-7 different ex eligible gyms in a week and try to get lucky?

If you don't have one powered up, I am tempted to say the question "Should I power up Mewtwo?" should be answered by "Yes" without further details.

To go a little more in depth: there is no such thing as a bad Mewtwo. Even a 10/10/10 Mewtwo is still a fantastic fighter. Considering it can have different uses it's even useful to have several ones if possible. I myself have only two, powered up the first one with PC/SB and considering powering the second one with C/P as a psychic specialist (standby for now cause I don't really need it). Several things can get to lean towards "do" or "don't":

* Do you need Mewtwo as a very strong generalist and don't have a Rayquaza? If yes, do.
* Do you need Mewtwo as a specialist? If so, do you need it now? If yes, do, if not just wait until you need it and then power up your best one.
* If you just got your very first Mewtwo, are you likely to be able to attend more EX raids in the future or was it a coincidence? If you have a chance of getting another one and don't need it right now, don't.

I think it's as simple as this...do you have a regular EX gym? If the answer is yes, then no. I was in the same situation with my first Mewtwo, which was also a 73%. But knowing I had that gym in a busy area, I waited. My next one was 87% with pc/sb, the moveset I wanted, so I'm in the process of powering it up. (FYI I am 4 for 4 on Mewtwo on 2 accounts, so he seems fairly easy to catch.)