You go on liberty island. But first you need the liberty pass event
^that's for victini... -_- for keldeo you will need to keep your eyes out for an event that gives you a keldeo.
Chat with our AI personalities
You can get Keldeo from a special event. It's by using the Mystery Gift.
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.
Keldeo is a Water and Fighting type pokemon.
In Pokémon Black and Pokémon White, you will need to take Keldeo, Cobalion, Terrakion and Virizion with you to the Moor of Icirus. Once you're there, a cutscene will happen that will involve the teaching of Secret Sword to Keldeo.
Yes, Keldeo is a legendary Pokemon.