trade it.
no, but you can get munchlax then evolve it in to snorlax, the way to get munchlax is from honey trees 4 of them contains munchlax depending in your secret ID I don't know what is it but the only way I got munchlax is from the global terminal
the easiest way is to hack.
With a Budew.
Breed snorlax.
Either cheat or "chain" 40 pokemon.
You can get munchlax in certain trees but it is really hard to get out I heard there are only four trees which contains munchlax depending on your secret ID there is a quicker way get one from the Global Terminal I got one like that named cab
Max out Munchlax's happiness and he will evolve. The easiest way to bring up happines is by having the Pokemon in your party and make sure it doesn't faint. Also don't use the organic medicine as that brings down happines.
a staravia or any Pokemon with intimadate will help and use pyschioc type moves and battle strong!!!!!!!
the easiest way; in hearthome city, talk to a fat hiker and he will give you an egg and when that hatches then it will be a happiny.
you can't capture it in soulsilver but you can trade it from pearl,diamond,or platinum
You can migrate it from any game boy game, or you can catch a munchlax then evolve it. To catch a munchlax you put honey on the tree thing, but there is only 1% you will catch it that way. So, the easiest way to have one is to trade on GTS in Jublife city. Have Fun with your Snorlax! =-)
I'm pretty sure that wild Growlithes are around the entrance to Stark Mountain in Pokemon Diamond/Pearl/Platinum.