What is the best pokemon black team to beat the elite 4?

Well 1st of Where is your starter pokemon? All 3 starters would be a little help full for the Elite 4 especially Tepig!, As you know the Elite 4 consists of The following pokemon types: psychic, fighting, dark, and ghost type, that being said I think you should keep Krookodile for the psychic trainer, get a Gothitelle for the Fighting type trainer, for the dark trainer a fighting type like Conkeldurr Sawk or Throh would be good (Scrafty is also good but since its half dark type its also week to fighting types) and for the ghost type trainer they are weak against ghost types (yes ghosts are weak against other ghosts) and dark type (Zoroark or Chandelure are really good also Cofagrigus) I Would take out Stoutland & Swoobat since they arent the best pokemon but its up to you!, Btw you might want to raise you're other pokemon to level 50 as well, the 2 Rotational Battles in Opelucid City could maybe help? Anywho Sorry this is so long but best of luck in building your team! I Really hoped this helped! =)