Okay, well, as far as I know, it's
Twilight Sparkle: Dusk Shine
Pinkie Pie: Berry Bubble
Rarity: Elusive
Rainbow Dash: Rainbow Blitz
Fluttershy: Butterscotch (I tried to come up with a better one but I couldn't)
Spike: Barb
Applejack seems to have the same name, but I've started calling the stallion version Braeburn (it's a type of apple, just so you know.)
Also, I thought this suited Princesses Celestia and Luna
Princess Luna: Prince Artemis
Princess Celestia: Prince Apollo
Hope I helped!
Edit: I forgot that Braeburn is actually already a character (he's a cousin of Applejack's.) Whoops?