Sonic/Goku should be obvious; Tails was meant to be somewhere in-between Bulma (extremely tech-savvy) and Krillin (best friend of the main character), but she ended up mostly Bulma. Amy--well, technically she'd be Chi-Chi, but since I'm going at least partially off of StS-logic for this series, that would make things...awkward.
Both Sonic and Amy's attire was based off of the Saiyan Hero and Heroine from the Dragonball Heroes games; Tails's on Bulma's various outfits, with the boots being an attempted nod towards Krillin. Also picked the Yellow Chaos Emerald as the one her radar detected, since it's the closest one in colour to the Dragon Balls (not counting that weird Orange Emerald, or those red Dragon Balls that some DBZ toys were packaged with).
The biggest challenge with Sonic's outfit was making it obvious which character he's paralleling without giving him pants.
Got anything actually relevant to the pic's subject to say?