um i don't think you catch munchlax in this game. you can get snorelax however. when you get to vermillion city. you'll see snorelax sleepin on his fat @$$ blocking the way into the underground route or ditto cave wutever its called. you have to get some kind of Flute to wake him up. then ya battle him. just so ya kno hes a real pain in the @$$ he has giga impact leftovers, ice beam i think or some other attacks. hes a problem unless you have a good Pokemon for him. when you find snore lax i believe he is in the level 40's or above. give snorelax i believe a full incense to hold, and then breed him with ditto. the voila! you've got yourself a munchlax. ;) hope this helps!
You catch it on Route 45 by a Swarm.
route 34
a pokewalker route.
You catch Houndour at night on route 7 in kanto
You can't, but you can catch gligar on route 45
You can find it at Route 22, Route 26, Route 27, Route 28, Mt. Silver and Safari Zone
in kanto at route 10
in Pokemon soul silver catch it in route 36, route 37, and route 48. (Note that i don't know if it is the same for silver)
its on the same route as the daycare center
In Route 2, 30, 31, and 37.
The easyest place is route 36.
You catch Snubbull in Route 37 and 38