93% 15atk 2500CP DT/DM Dragonite power up?

Absolutely.

...

But I'd TM it to Outrage.

I'd hold off powering up for the time being. If it truly is 2500 CP, and no higher, then it could be a prime candidate for use in the PvP Ultra League.

If you're lacking in Dragon-types, then yes, go for it. You might want to leave it at 2500 CP for use in the PvP Ultra League though. Also, no need to TM it right now. Once PvP hits, you'll be able to unlock a second charge move, which can be Outrage. Draco Meteor is a legacy move, so you won't be able to get it back. I'd say keep the moves as is, so then when PvP drops, you can have both moves.

I'm like 99% sure that dnite won't b very good in the UL. A kingdra will be vastly superior to that low level dnite under 2500. Mayb u dont fight much in master league cuz trainers with multiples of max legendaries will have a stupid advantage. Anyways what does it cost u to wait until pvp releases and GP does a full analysis on PVP? Better to focus on obtaining more resources then using them now only to regret it later. However if u dont have any dnites and need it to raid or battle gyms go for it.