What can Empoleon do to Kingdra? Toxic it?
ice beam or grass knot does a fair amount of damage to offensive versions sure it doesnt ohko(maybe not even 2hko lol) but it walls kingdra pretty good and will get him down.
on topic: Kingdra seems to stay pretty much the same, but the enviroment around him seems to be pretty kind to him providing him with endless rain through politoad.
Boiling water will see some use on the defensive sets and another pokemon now resists its dual stab (sadly for kingdra it seems to be pretty good on the defensive side).
His movepool may be shallow but he gets everything he needs in form of Resttalk/Dragon Dance/Waterfall/Surf/Hydropump/Dragon Pulse/Outrage/Draco Meteor and the occasional Hidden Power on Specs sets, sure things like thunder or flame thrower wouldnt hurt but he will do well without them.
Also dont forget his Chest rest set
Kingdra@Chesto Berry
Nature:Jolly/Adamant
Evs:192 HP/64Atk/252 Spe(forgot the exact ev set but i bleive it was something like this)
-Dragon Dance
-Outrage
-Waterfall
-Rest
Simple Strategy get as many DDs as you can while your opponent statuses/attacks you then use rest and start to sweep, its a pretty good late game sweeper if you manage to get some DDs up especially because he isnt killed of that easy by priority.
Edit:
@iruchii of course your right he is a much better stop to kingdra just wanted to show how empoleon beats him not that he is doing it better