Uhh I know this is a pretty old comment, but g1 is from the 1980's... Pinkie Pie didn't exist in g1. Pinkie Pie is from g3, and so is Scootaloo. They're also in g3.5.
However, g1 is the generation Lauren Faust based MLP FiM on (because she was a fan of g1) although Hasbro lost copyright to their old characters so she used g3 ponies: Rainbow Dash used to be fashionable in g3 and g3.5, but Lauren put Firefly's personality (who's from g1) into g4 Rainbow Dash and violá! Scootaloo was Cheerilee's little sister, and Sweetie Belle and Scootaloo had their cutie marks. Rarity was a fun-loving unicorn princess who was pink and young, etc etc...
In MLP FiM g2 doesn't actually exist. G2 was just a toy line, but there is such thing called MLP Tales... Although that is still technically g1, but most people consider it a "g2".
Oh, that's good, because that gen (although I didn't watched G1 shows) needs more love, and also, it would do two things: 1. Bring up the nostalgia of most fans of MLP. 2. Butthurt Rabid Bronies, who will say things like "STOP SPAMMING DA WITH PREVIOUS GEN PONIES! G4 RULZ!!!!11ONEONE!" on each picture.