I can imagine their friends’ reaction:
What was left of the Mane 6, Sonic, Tails and Knuckles were looking for Pinkie Pie and Amy.
Rainbow Dash: AAAAAAAARGH! This is taking FOREVER!
Twilight: We’ll find them, Rainbow. Just calm down.
Sonic: Pinkie and Amy HAVE to be around here somewhere.
Tails: Have we tried looking at Sugarcube Conners?
Awkward silences
Knuckles: And why didn’t we think of that?!
They headed indoors of Sugarcube Conners and enter Pinkie’s room seeing….
Mane 5: PINKIE?!
Team Sonic: AMY?!
The two pink females gasped when they saw their friends.
Pinkie Pie: Hey girls! Amy and I were having a lot of fun wearing poofy diapers!
Amy: I don’t know what Pinkie means, but wearing diapers are humiliating.
Pinkie Pie: It’s not that bad, Amy! (To the others) Wanna join us?
Fluttershy: Um… I wouldn’t mind.
Tails: Eh… okay.
Knuckles: (blushes embarrassed) Fine! As long as we don’t get those diapers.
Applejack: Ah guess it won’t hurt to try.
Rarity: Fine! As long as I wear a stylish diaper.
Rainbow Dash: Eh… this might be humiliating, but… I wouldn’t mind wearing diapers.
Pinkie Pie: What about you, Twilight and Sonic?
Twilight: Um…. I have to do my duties as the Princess of Friendship.
Sonic: And I’ll have to be busy stopping Eggman! See ya!
Sonic and Twilight left, leaving the rest of their friends to join Amy and Pinkie.

Seems normal… Just, that’s a giant ball.