This is mostly so I can keep track of the ponies I remember from childhood, and the G4's I don't have yet. I'm not actively seeking to buy these right now.
G1
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Wind Whistler
Lickety Split
Fizzy
Baby Lickety Split
Little Flitter
Sunnybunch
Sky Rocket
Twinkler
Baby Sunribbon (My brother swears up and down that we had Rainbow Dash growing up, but G3 is too new for that. I'm pretty sure Baby Sunribbon is the 'Rainbow Dash' we remember.)
G3
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Rainbow Dash (Just in case.)
G4
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Apple Bloom
Scootaloo
Sweetie Belle
Cherry Pie
Diamond Rose
Playful Pony Luna
Daisy Dreams
Rainbow Flash
Skywishes
Star Swirl
Starbeam Twinkle
Sweetie Swirl