Answer 1

Nope...
It is impossible to catch without an event.
You can still trade for one.

Comments

good answer Up-Vote

Answer 2

Actually, there is no other way to catch it without an event. Unless, you get it from a trade or from an Action Replay (AR). (Hope This Helps!)

Answer 3

When B&W first came out you could get a free celebi at gamestop, but only at events or trade now.

Or action replay/poke-nav