Event only. Keldeo hasn't even been released yet (June 2011)
Chat with our AI personalities
Keldeo is event-only pokemon. This means that Nintendo will distribute Keldeo for players to catch. The only other way is to cheat with Action replay, gameshark etc.
You can't catch keldeo in the moor belive me i tried it did't work
There is no place where you can catch a level 100 pokemon unless you use some cheat device. (Such as an action replay)
It will be in Special Events in the future. Hopefully, soon.
It learns Sacred Sword at level 43.