They were sold in toys r us around here and maybe in toys. There were a few types:
Earth ponies with light up symbols
Earth ponies no light up
Earth ponies with 3d music notes that when pressed played music
Pegasus light up
Pegasus no light up
Some had necklaces with gem hearts I don't remember if the gems light up though.
I bought a few back in the day. They were available during the g2 run on mlp! And they came on a card and maybe boxes? I remember seeing tons and tons at toys r us when g2s were out. I think I had 5 or 6 of them!