Peppy Gals or Universe Survival Saga cards increase the chance of drops. The following characters have both of those categories and double the drop chance.
AGL LR Characters
Saiyan Spirit Super Saiyan 2 Gohan (Youth)
Eternal Rival Super Saiyan Vegeta (GT)
[Tight-Knit Fusion Fighter] Super Saiyan Kefla
How to get/farm Goku 3 medal
Breaking Barriers Super Saiyan 2 Goku (Angel)