Pokemon Soulsilver glitch?

I'm confused about pokemon Soulsilver, I was in the Safari zone because I found a larvitar in there at level 17 in there, the other day I found one at level 42. Is that suppose to happen? I was unable to catch it because it fled after the second ball. also is there an easier way to catch them? like whats the benefits of "bait" and "mud" in the safari zone? also Sudowoodo reappears after a certain amount of time, does that mean Snorlax come back too? Finally whats the purpose of the gym leaders from Diamond and Pearl being in the Kanto region? I ran into the guy who wears the mask he gave me 3 mask for the fashion case. I'm kind of confused.