Would you power up this?

No, unless cloudy weather is rare for you. You also need Dynamic Punch for it to be worth anything.

We had loads of clouds week after Christmas, but I evolved just one. 13a/12d/7s level 34, 2444cp c/dp (born w/Bullet Punch). I have 184 more candies for some other ones. I actually don't know what'll spawn frequently now, some of the better species might be really limited, even in the right kind of weather. I just saw one Ralts today and I clicked the go plus before I could see the mon...fled. I'd save up candy instead.

Also going with no.

Weather boosted Makuhita are quite common, getting a good one is rare, but it will happen again. Use this one as is and keep hunting for the truly amazing one.

It depends on your resources (candy and dust), and how much you are in need of good fighting pokemon.

This is a very good Hariyama; stamina is already huge, so it is the least important IV. If you already have several C/DP Machamps, then maybe you don't need this one powered up, but if you need more fighters to raid Tyranitar or Absol, this is a good one. Level 35 will get you to the important quick-move breakpoints, so that is the level I would target.

Powering it up from level 29 to level 35 will cost 72K stardust and 72 candies, so it will not be cheap, but you will have a very useful mon.

However, the other consideration is the number of charge TM's you have. There is no guarantee you will get DP on the first try...or second or third or fourth. You might burn through a lot of TM's. I currently have a karate chop/close combat Machamp on which I have spent seven TM's trying to get DP, and I keep toggling back and forth between CC and HS. At this point, I have given up, because in the meantime, I have evolved three good Hariyamas with DP, and caught two boosted (level 25) Machamp raid bosses with DP. So I no longer have the need, and I spent all those TM's for nothing. Just something to consider.

Just toss it in a gym as a defender, then leave it fainted.