Swanna or Samurott? Pokemon Black Version?

Now these are both VERY good Pokemon. It depends how you teach there moves and how YOU use them not how other People use them, OK.

Swanna is a great all rounded Pokemon and is usefull for Surf and Fly. These are both good Hm's and are used quiet alot. So Swanna is helpfull in alot of cases. It learns great moves such as Hurricane, Brave Bird and such. A moveset for Swanna is: Fly, Surf, Hurricane and Brave Bird

Samurott is a base Water Pokemon so it does'nt have that little extra kick, you know. Samurott also learns good moves and is VERY well rounded. You can teach moves like: X - Scissor, Megahorn, Body Slam etc. These bug moves take out the grass weakness so you don't have as much to worry about.

So I'd say Swanna because of its Dual type and all roundedness. Btw, Before entering The Pokemon League have your Pokemon above level 50 OK! Hope I helped!

Samurott