Instructions
Start a new game and name your trainer to get the default red Trainer Card with no stars.
Beat the Elite Four to earn your first star and get the blue Trainer Card.
Finish the National Pokedex, capturing all non-event Pokemon. In the end you will have 484 Pokemon in your Pokedex, not counting any of the event Pokemon such as Mew, Arceus, Jirachi or Celebi. This will earn you another star and the green Trainer Card.
Find five Shiny Leaves with one Pokemon, which can be a time-consuming process. Talk to the Pokemon following you on the worldmap while in tall grass, and, in rare instances, it may find a Shiny Leaf. Once you've found five you'll earn another star and turn your Trainer Card pink.
Play the 10 Pokeathlon events and beat the records in each one to get the silver Trainer Card and your fourth star.
Head to the Battle Tower and get a 100-win streak for your fifth and final star, earning the elusive black Trainer Card.