the event Legendary Beasts what are they and how do you obtain one??

1. Shiny versions of Raikou, Entei and Suicune, the legendary beast trio from GSC.

2. You can't, at least not a new one. They were given out at GameStop as a wireless event several months ago. If you really want one, you could try asking someone to trade with you.

With these Event Pokémons you can caught a Zoroark at Lostlorn Forest. If you bring them to Lostlorn Forest, a woman that lives there will attack you. That woman is Zoroark. It wil be at level 25 and comes with the ability Illusion.

Also, these Event Pokémons come with some good moves. Specially Entei, that knows Flare Blitz.