Once more you are given special Trainer Stars after completely special tasks, which also changes the colour of your card. Do note the card changes with the number of stars you've collected, but not necessarily which ones.
The accomplishments necessary to get a new star are as follows:
Defeat the Pokemon League Champion for the first time.
Jump 200 times in Pokemon Jump and collect 200 berries in Dodrio Berry Picking
Complete the Kanto Pokedex, except for Mew.
Complete the National Pokedex, except for all Mythical Pokemon.
Finally, you can have a print taken of your Pokemon party for $50 at the Rocket Game Corner in Celadon City. Your options for print colours are: Normal, Black, Pink, and Sepia.