Lvl 10 96% Larvitar worth evo+pwr up?

I powered up a level 8, 98% Larvitar - however that was from community day (so it was exclusive move smack down), and even then I sort of regretted it at the time (until the triple stardust community day, then I think it was good).

I think the only reason it was worthwhile for me though, is because it had smack down. Doing one now seems senseless. Raid Tyranitar whenever you see it, and you'll get a 96% or higher eventually (I've gotten a 98%, as well as two 93%s, since the community day). You'll also get loads of candies from the raids to power them up. Find a duo-partner and trade all the lower IV ones with eachother to try to get a lucky one and to reroll IVs.

Basically, I think from a candy perspective it's fine - you can raid Tyranitar for 20 candies per raid. Once you start looking for them, the candies come pretty easily. However the stardust is really not worthwhile, when you can get a lucky one or a level 20/25 raid one to start from instead.

Maaybe if you do a bunch of raids and get loads of candies and don't get any better ones, then consider doing it. No reason to rush though - there's no urgent need for a double dark TTar right now (and you can't get the rock one).

Nope not worth the dust or candy

You have enough Ttar
Only do it if you're drowning in stardust and have enough candies for it

It probably isn't worth it to power it up or evolve it - until such time as Niantic allows us to use TM's (of some kind) to get Community Day exclusive moves. Personally, I'm keeping about 4 Larvitar with Attack 15 and decent IV's (including 1 Lucky!) just for that possibility.

However there is another option - trading those lesser or unpowered Ttars for other Ttars. You get at least 1 extra candy for the trade AND you get a chance to get a Lucky Tyranitar. You've got 5 or so Ttars that I'd suggest trading with others to try to get a Lucky Ttar. Or the next time you do a Ttar raid, if you get a bad one then trade it with someone else at the raid who got a bad one.

(Yes, I've been converted to the cult of the Trade; getting an 89%Attack 15 Larvitar and a 93% Attack 15 Tyranitar as my first two Lucky trades convinced me that it's worth it!)