The ponies I'm missing are arranged by generation, subset, and (vaguely) highest to lowest priority. If a set isn't on here, it either means I'm not avidly collecting it or I've completed that set. Because I do a lot of restorations and customs, I'm not picky about condition -- about the only things I don't like in a collection pony are cancer and regrind.
Lists last updated: March 20, 2016.
Party Gift Packs: Celebrate
Summer Wing Ponies: Buzzer, Glow, Little Flitter
Windy Wing: Flurry, Starry Wings, Moon Jumper, Whirly
Loving Family Ponies: Daddy Bright Bouquet, Baby Bright Bouquet, Mommy Sweet Celebrations, Daddy Sweet Celebrations, Baby Sweet Celebrations, Mommy Apple Delight, Daddy Apple Delight, Baby Apple Delight
Precious Pocket Ponies: Sweet Pocket, Bubblefish, Li'l Pocket, Bunny Hop
Secret Surprise Ponies: Secret Star, Stardazzle, Secret Beauty, Pretty Puff
Sweet Talking: Chatterbox, Talk a Lot
Flower Fantasy: Flowerbelle, Sweet Blossom, Love Petal
Colorswirl: Lovebeam
Birthflower Ponies: Morning Glory
Wedding Ponies: Satin 'n Lace (dark magenta), Satin 'n Lace (So Soft)
Pretty Mane Ponies: Scribbles, Dabble
Baby Sisters: Li'l Sweetcake, Li'l Cupcake
Baby Birthday Ponies: Baby Sugarcake, Baby Gametime
Twice As Fancy Baby Ponies: Baby Dancing Butterflies, Baby Milky Way, Baby Sugarberry, Baby Love Melody, Baby Sweet Tooth, Baby Up, Up, and Away
Current's Valentine Day Twins: (white w/red hair), (purple w/pink hair)
Mommy and Baby Pony: Mommy, Baby
Individuals: Stockings the Holiday Pony, Clipper, Baby Blue Ribbon, Li'l Tot, Chuck E. Cheese Baby Pony
Adults: Cascade, white Tootsie, Honeycomb, Snowflake, Hopscotch, Tutti Frutti, Rosette, Sweet Clover, Good Weather, Princess Sparkle
Babies: Baby Applejack, Baby Bowtie, Baby Brother Bright Bouquet, Baby Sister Sweet Celebrations, Baby Billie, Baby Susie, Baby Katie
Mountain Boys: Ice Crystal, Lightning, Sunburst, Tornado, Fireball, Thundercloud
Flower Ponies: Daffodil, Tulip, Snowdrop, Bluebell
Playschool Babies: Baby Count a Lot, Baby Alphabet, Baby Pictures, Baby Schoolbag
Schooltime Ponies: Musictime, Paintingtime, Sportstime, Playtime
Romance Ponies: Love Token, Love Story, Love Letter, Love in a Mist
Cookery Ponies: Cherry Sweet, Vanilla Treat, Sweet Delight
Seven Characters: Starlight, Clover, Patch, Bon Bon, Sweetheart, Melody, Bright Eyes
Bedtime Newborns: Moondream, Sunset, Stargaze
Hairdo Ponies: Beautiful Bows, Starlight, Bangles
Family Ponies: Sunbright Family, Berrytown Family, Meadowsweet Family
Nurse Ponies: Tenderheart, Sweetheart, Loveheart
Great Hair Ponies: Ringlets, Highlights
Sweetie Babies: Liquorice, Candy, Lollipop
Jewellery Babies: Sapphire, Ruby, Diamond
Seaside Babies: Splish, Splash, Splosh
Surprise Newborns: Bouncy, Cuddles, Snoozy
Dutch Ponies: Any
German Rainbow Ponies: Raindrop, Nightlight
German Babies: Cherries Jubilee, Hopscotch, Buttons, Lemon Drop, Honeycomb, Blubberchen, Schlummerlein, Wuerfelchen
Greek Ponies: Any
Macau Ponies: Any except peach Peachy.
Super Long Hair: Beach Belle, Rainbow Bubbles, Snowdrop Swirl
Playset Ponies: Darling Dahlia, Anchors Away
Fancy Hair Pony: Rainbow Treat
Breezies: Unnamed UK purple and pink Breezies, Zipzee, Snippity Snap, Day Lily, Willow Wisp, Knick Knack, Pink Petal, Orange Flower, Dancing Daffodil, Zippy Zinnia, Purple Petunia, Darling Dayflower
Birthflower Ponies: March, April, May, June, October, November, December
Target Babies: Winter Ice, Northern Lights
Special Editions: Superhero, Ninja, Villain, Graffiti, Tattoo, Ribbons and Hearts
Fancy Trotters (gold tinsel in tail): Daffy, Jazma, Rosette, Golda, Lily
Fashion Parade (sparkles on rump): Goodie, Royal, Ribbon, Dancer, Hopper
Classic Horses: Shadow, Starbright, Wildflower, Misty Meadow, Twilight, Honeycup
Bright Beauties (two color tails): Starry, Sunset, Glowie, Halo, Sunbeam, Seabright
Animals: Just the unicorns (looks like blue and pink -- I don't know their names or if they were made)
I would really like to have the ribbon and charm they came with too, but I know that's asking way too much.