Kingdra is one that's been mentioned here and there as a potential powerhouse for the 2500 tier, and I'm inclined to agree. It's obscure enough that some people won't know what it's capable of, and the dragon/water typing is tricky to counter. It's stats are solid, and between Outrage and Blizzard, it packs a strong STAB move and good counter-coverage. I think Kingdra will definitely be making some waves in the Ultra league.
GamePress
Kingdra anyone?
Anyone have thoughts on Kingdra for the 2500 CP league? It has really good typing (only weak to dragon and fairy) excellent moves (Outrage, Blizzard, Hydro Pump), well rounded stats, and it hits just under 2500 at level 36+ (depending on IVs). I expect that most players won't bring fairies right away for fear of Metagross. At the same CP, it will be tankier than Dragonite with just slightly lower attack and better coverage moves. Have I discovered a hidden gem?
