To unlock cards featuring artwork, you must complete challenges in Striker Challenges mode:

Effect - Code

Bowser Card - Beat Challenge 09
Bowser Jr. Card - Beat Challenge 11
Daisy Card - Beat Challenge 05
Diddy Kong Card - Beat Challenge 12
Donkey Kong Card - Beat Challenge 03
Luigi Card - Beat Challenge 02
Mario Card - Beat Challenge 01
Peach Card - Beat Challenge 04
Petey Piranha Card - Beat Challenge 10
Waluigi Card - Beat Challenge 07
Wario Card - Beat Challenge 06
Yoshi Card - Beat Challenge 08