A unicorn creator with the g1 and g2 characters as grown up/mother and the g4 as child.
Technically it would make sense. I liked the g2 design the most - tall and sleek. A pity they made no tv show ...

You can create as mother: Bonbon, the Last Unicorn, Honey, Waterlily, Heart Throb, Twilight, Peachblossom and Rosedust.
As child: Rainbow Wishes, Luna, Rarity, Cheerilee, Unicorn Foal, Rainbow Flash, Twilight Sparkle and Rainbow Dash (man the producers really like rainbows).

PS: I know there are cutie marks missing - its hard to get good images of the old characters marks.
Music: "Last Unicorn OST - Haggard's Unicorns"