you can't
Yes you can find it at nightime.
You can find it at Faldera Volcano.
yes you have to do the Pokemon league
You have to Trade it from fire red or leaf green.
Mt. Silver. Lavitar is around level 20!
Larvitar can be found at Mt.Silver, you access this place when you have defeated the Pokemon League.
mt. silver and you can rarely get it in Safari Place. x
Pokemon ruby's version IS Pokemon ruby.
Larvitar is exclusive to DP. You can either Trade for one, or you can migrate one.
You can't
Mt. Silver
safari zone