Actually, you'd be impressed on how much better the card would look if you gave it a solid border. Like. It looks good, but literally just add a border and it'll look even better. Like don't change the embossed borders it has now or anything. Just add a border.
Yellow border.
Black border.
Some weird glow border that doesn't look good in photos (but gives it a "worn" look)
This is just me here, but I'd suggest doing colored borders by their affiliation within the game's plot - but keep it simple. i.e. Mario, Yoshi, Rosalina, etc. have white borders as they're good guys and Bowser, Tatanga, Wario, Goombas, etc. have yellow borders as they're antagonists.
Yellow border.
Black border.
Some weird glow border that doesn't look good in photos (but gives it a "worn" look)
This is just me here, but I'd suggest doing colored borders by their affiliation within the game's plot - but keep it simple. i.e. Mario, Yoshi, Rosalina, etc. have white borders as they're good guys and Bowser, Tatanga, Wario, Goombas, etc. have yellow borders as they're antagonists.