Dragonite with DB+HB

It's not the best but it will be just fine as a generalist attacker.

Just a great attacker. It will be a better allrounder than any other attacker besides a A-rated Dragonite.
HB has two problems:
(1) lack of STAB
(2) long time to cast
The first one is somehow compensated by great ATT-Stat of dragonite and great power of HB itself; The second one hurts somehow, you may miss to dodge a charged attack while casting, but as dragonite has really good defensive stats too, it will not faint this fast.

IMO: Gratulations to this dragonite, power him up!

This moveset is 3rd for attacking and 6th for defending.

That said, he is still a great attacker.
If already high CP, I would use him without powering him up. Because I soon as you get a DB/DC or even a DB/DP one (and you'll get one if you keep playing), this one will became a second choice.
I dont like spending dust and rare candies on a suboptimal moveset mon.

If lvl 20 or below, i would keep him as prestiger.

Quick answer for comparing DC/DP/HB: (assuming neutral damage)
1. When spamming attacks (without any dodge), three perform almost the same;
2. When dodging specials, HB performs noticeably worse than DP, which performs slightly worse than DC;
3. When dodging all, HB performs worse than DP, which performs worse than DC.

In conclusion, the more you dodge, the worse HB performs compared to DP or DC. Also, when killing Dragonite, HB performs worse than DP and DC.

Any Dragonite with Dragon Breath + any charge move and high IV's is a must to power up for me at least until level 30, around 3k CP, then you can start saving candies for your next one until you get the DB/DC combo if you want, I have one with that moveset, 98%IV maxed to my level (34), and it is a beast for sure.

Chances of getting DB/DC are not that high (I know what I am talking about, I have evolved 4 Dragonites, still no DB/DC), and if you are not close to a Dratini spawn and took months to get one I would say don't "waste" those 124 candies you have just used and power this up and enjoy it, only dodging special moves you will melt all mons in gyms.

Congrats! Dragonite is actually one of the less stressful evolves. It's very simple, he's either an attacker (DB) or a defender (SW). His base stats skew towards attacking though. It's all up to his quick moves... so essentially all you worry about is a 50/50 outcome. His charge moves don't mean much as they're all powerful. It's just a matter of your own skills and tactics on how to use them.

I've got high end maxed out Dragonites with every moveset, and while DB/DC is just flat out the best attacking moveset, anything with DB is still really good. Hyper Beam is a huge amount of damage, and even without STAB it's still not far behind the dragon attacks.

Enjoy :)