Yes. If yu beat them 1ce, they get Level 65-80 strong
After defeating the Elite Four once, their Pokemon are much stronger than before, and with new Pokemon. There is no new Elite Four to battle, though.
beat elite four rematch
lance
They don't get sronger, but your Pokemon will get stronger if you battle them a lot.
A lv:100 venusuar!!
The elite four
Beat the Elite four and the Champion.
Legendaries or Feraligatr, Ampharos, and Heracross.
You have to get an action replay and battle one of the elite four
get stronger then you are before
train like any other game
you have to beat the elite 4 89 times