Someone should write to Nintendo about that. Seriously.
Yeah, but do you think they would take it seriously or just throw it away without reading?
They are obviously-still- being bombarded with G/S/C remake questions.
but i'll take a whack at it, as soon as i found out their yahoo! mail.
~ontopic~
They are, like previously said, only in route 7 and are rare.
why they put 2nd season pokemon in the first season and was not found in the 1st season is unknown, but a stupid move for nintendo.
but they possibly put houndour in kanto because its overpowered. you would have no trouble whatsoever with the E4 since houndour can destroy most of them.
i don't know...maybe the wild pokemon were originally all in jhoto but migrated to Kanto.
that is the most logical answer that i can think of.
EDIT: you can get a friend to give you a houndour, but other than that, you are on your own with catching them.