>>11976214
>Like even storywise, was the fuck is Big even doing with Amy and Cream?
They just kind of met up on happenstance following the tabloids. Froggy and Chocola disappeared, Sonic is apparently involved, Amy loves a good mystery/adventure and is friendly enough to let them join her on her never-ending Sonic-chasing quest and knows the arrangement is mutually beneficial, win-win.
out-of-universe answer: They wanted to pair up Cream with Amy from the start but thought Rouge deserved to be in Shadow's team so they needed a quick filler and gave Big a second chance.
>their campaign is completely unnecessary.
Amy gains team-managing experience that she needed to grow further, and it's through copying Froggy and Chocola that Metal Sonic gains Chaos' DNA so their disappearance is somewhat important to the plot.
>maybe he met them and they became friends in one of the comics and shit, I don't know anything about Sonic's non-vidya media
You'd get more confused if you dabbled into non-game Sonic media for answers since they're AU for the most part.