I have a feeling they'd be great friends:
Sonic and Rainbowdash- They'd fight over on who's the fastest- kind of like a friend/enemy relationship.
Trixie and Silver- Silver would show Trixie his telekinesis and Trixie would show Silver her new magic tricks.
Amy and Pinkie Pie- They'd have parties, dur.
Gilda and Shadow- Shadow and Gilda would try looking cool in front of others
Liketheyalwaysdo.Knuckles and Apple Jack- Knuckles'd try to prove to Apple Jack that he's stronger than him- Hefails.
Tails and Twilight- Always fighting over magic and science. Twilight arguing that magic is real and Tails arguing back that there's no such thing as magic, and that's it's pure science.
Derpy and Big the cat: They'd be derpy little friends together.
WHO AGREES WITH ME?