I recently got a victini but it says it's #000 in the pokedex. Why?
That's the way Game Freak made it. Probably to make Victini seem more like a mysterious, unknown Pokemon.
>Because Victini was given out on launch day (both in Japan AND America) and was available early. If he turned out to be #153, it would give away that there are at least 152 other Unova Pokemon early. By making him #0, they keep the total number more of a mystery (at least to those who didn't read up on the leaks online.)
This is not my own idea: I found it on a forum here