Because they are rare
Some consider it Legendary, as it is very rare, but it is not actually a Legendary.
You can get the Japanese Pokemon Black & White in some shops in Japan, or you can pre-order Pokemon Black & White on a site called Play Asia.
yes there are some
Lucario riolou zorua zoarak zangoose seviper
I have Pokemon Black, and as far as i know you cannot catch event legendarys without an event (eg. Genocect, Zorua). You cannot catch some Pokemon on the game, but Pokemon White can, and White can't catch some Pokemon that you can catch on Pokemon White. Lol!
well, no one can really answer that. you see, Pokemon black/white just came out, and there are some really rare ones in there. most of the rare ones are equal, as there is one extremely rare Pokemon in every game. but right now, i would probably say mew or celebi. hope my answer helped!
There are no codes
I know there are others, but here are some examples: Pokemon Black-Gothita, Vullaby, Cottonee, and their families Pokemon White-Solosis, Rufflet, Petilil, and their families
some show up in white forest
there are not very many pokemon black and white action replay codes.
you cant find Genosect in Pokemon black or white Genosect will be obtainable in a Pokemon event some time in the future
Have the Pokemon types you will need most in the place you are going.