As you accomplish more along your journey, your Trainer Card will change colors and rise in rank, depending on completing certain tasks. After completing one task, it will rise in one rank, but there are some tasks that cannot be completed until beating the Elite Four. You must do these tasks:
-Become Pokemon league Champion
-Complete the Hoenn Pokedex
-Collect all the gold symbols in the Battle Frontier
-Win one ribbon in all five of the Master Rank Pokemon Contests.