Type houndour into your search browser and the top result should be bulbapedia.com and it will have everything you need to know
try going to Altering Cave. sometimes there are Houndour there.
Safari Zone.
You can't you have to trad with Pokemon collesium or gold.
Piplup does not exist in Pokemon LeafGreen or FireRed.
No, you cannot find cyndaquil in LeafGreen.
you should go to gamestop
LeafGreen version does not have Growlithe.
Level 28
In the grass...
You cannot catch houndour in Pokemon leafgreen either get one from Pokemon emerald or Pokemon colosseum.
there is no such Pokemon
That item doesn't exist in leafgreen.