The only way is the Pal Park.
You can catch Seviper in the Marshland area of the Johto Safari Zone.
grass hysteria
in epoisode 35 of the Pokemon the legend of dartini
season 3 ep 10.
you can't catch seviper on Pokemon ruby (Pokemon sapphire only)
You need to trade seviper to firered from sapphire.
You don't, so sorry and you wont get on in there but if you do...
The only way is the Pal Park.
You can catch Seviper in Ruby, Sapphire, Emerald, HeartGold (IV), SoulSilver (IV), Black and White.
You can catch Seviper in the Marshland area of the Johto Safari Zone.
you go to the right of celestic town and use the poke radar
your family
You must trade one over from Pokemon Sapphire or Emerald. It is spelled Seviper, by the way.
Audino,Zekrom,Sawk,Throh,Kyreum,Tornadus,Seviper, and Zangoose. These are Pokemon you can catch on Pokemon Black. I think that's about it. also alomomola
Using action replay get the capture trainer Pokemon cheat and then an ace trainer near stark mtn has one
if you are talking about seviper, you have to trade from sapphire/emerald cause otherwise you cant catch it!!! But you have an advantage since u can catch zangoose while in sapphire/emerald you cant catch it!!!