Any use for kingdra?

Yea if you really like kingdra

For take down dragonite... yes... prestege gym... yes... just keep maybe gonna be big next cp rework

Also quite good against pure water types, like Vaporeon, because Kingdra double-resists Water and gets STAB on his Dragon moves.

Double Dragon Kingdra is "okay".

It preforms against Fire Defenders like using a normal water type. It preforms against Water Defenders using a normal grass type.

((You get Double Resistance, instead of 1 Resistence + 1 Super Effective)

Personally, I prefer the normal 1 Resistance & 1 SE over the double resistance.

However, because of it's versatility you could prestige/fight a water-fire back to back without swapping.

It's not as good vs dragons as many others (especially since you take SE back) but again, you could do a dragon-water or fire-dragon combo without switching.

All in all, it's always Suboptimal in my opinion in 1-1 match up. But because of it's versatility you might find gyms with 2 pokemon in row you want to use it vs.

PS: I still want Water Gun/Hydro on mine because while it doesn't have that versatility above. It becomes one of the PREMIER fire pokemon killers. (2 resistance + 1 SE)

Nope.
Use it for prestige or fun, but definitely not worth spending over 100k stardust to put it slightly above 2000cp.

I'm not a Kingdra fan for taking down Dragonites because if the Dragonite has dragon moves, the Kingdra takes more damage than, say, a Seadra. I like something like a Gyarados with double dragon moves more. As some of the others said, tho, it could be good for prestiging, depending on where you feel you have holes in your prestiging teams.