I would go back to 1987 in the UK and get Princess Amethyst, Rosedust, Fireball, Snuzzles version of the Grooming parlour and Strawberry Fair. I would keep them all moc/mib.
I would also hunt down 6 year old me and leave a note instructing her which ponies to buy and to make sure I keep all the accessories, especially the ribbons and puffy stickers very safe!