Big adventure
Tons of fun
A beautiful heart
Faithful and strong
Sharing kindness
It's an easy feat
And magic makes it all complete
You have my little ponies
Do you know you're all my very best friends?
Yes, I like Keldeo lots now shut up.
Keldeo's a pretty fun Pokemon. But it really came in at the wrong time. With BW2 giving us Tornadus-T, Thundurus-T and Amoonguss all in one fell swoop, Keldeo's potential has really taken a hit. That doesn't mean that Keldeo is bad by any stretch of the word. It's just not as easy to use as one would thing.
Take Terrakion, swap its offensive stats around and give it a typing that gives it additional STAB in the most common weather. In a nutshell, that's Keldeo. It's Hydro Pump is incredibly powerful after a Calm Mind or with Choice Specs. Secret Sword is incredible for it, as it bypasses Blissey who would otherwise fully stop it, as well as getting past Ferrothorn as well. Also, Keldeo is incredibly hard to change the weather against, as Ttar, Ninetales and Abomasnow all fall to a STAB attack. Keldeo may have a narrow movepool (Hydro Pump, Secret Sword, Icy Wind and Hidden Power is just enough for a specs set), but Keldeo's Specs Hydro Pump in rain is so easy to spam if your opponent lacks an immunity to it that it really doesn't matter.
Alright guys, let's talk ponies for a week.