I realized today that I don't have one of these! I thought I'd put grails at the top, and under that just a running list of ponies I don't have! I don't care about MIB for any of the generations and I don't care about accessories unless noted.
Big Wants:
G1
My Little Pony Tales ponies
Tropical Breeze (last flutter I need... mine has mold and a missing wing mechanism)
Twinkle Eye Bright Eyes
Roller Skatin' Pony Melody
Scribbles
Dabble
Rockin' Beats guitar combs (any)
Mountain Boys (any, duh, blargh)
Star Hopper
Star Dancer
Sky Rocket
Glow 'N' Shows (any)
Baby Paws
Baby Lucky Leaf
Baby Chuck E. Cheese
G2
Playset Morning Glory with the little reversible Cinderella outfit
G3
Dazzle Surprise
Licensing Show Rarity
Snow'El 2 (2007, with accessory)
G1
Year 2
Seashell
Sunbeam
Twilight
Starshine
Adult Sea Ponies
Sealight
Wavedancer
Year 3
Heart Throb
Starflower
Flutterbye
Confetti (walking pose)
Pinwheel
Trickles
Baby Ponies
Baby Firefly
Baby Glory
Adult Sea Ponies
Sea Breeze
Whitecap
Sea Mist
Wave Jumper
High Tide
Sand Dollar
Baby Sea Ponies
Splasher
Sea Star
Surf Rider
Tiny Bubbles
Year 4
Twinkle Eye
Galaxy
Sky Rocket
Pretty 'n' Pearly Baby Sea Ponies
Sunshower
Water Lily
Beachcomber
Party Gift Pack
Party Time
Celebrate
Year 5
So Soft Ponies
any
Twinkle Eye
Quackers
Locket
Mimic (bleeeeergh)
Tic Tac Toe
Bright Eyes
TAF
Love Melody
Up, Up, and Away
Sweet Tooth
Princess Ponies
Princess Starburst
Big Brothers
4-Speed
Salty
Quarterback
Slugger
Steamer
First Tooth
Baby Fifi
Baby Tic-Tac-Toe
Baby Sea Ponies
Salty
Dipper
Surfy
Sea Spray
Sea Breeze
Year 6
TAF
Merriweather
Buttons
Bonnie Bonnets
Yum Yum
Munchy
Princess Ponies
Princess Pristina
Princess Moondust
Sundae BEAST
Banana Surprise
Swirly Whirly
B'N'G
Bouquet
Curly Locks
Twisty Tail
any but Romper
Magic Message
any
Big Brotha
Wigwam
Chief
Peek A Boo Baby
Any except Snippy
Summer Wing
High Flyer
Lady Flutter
Watercolor Baby Sea Pony
any
Pony Friends
Cutesaurus
Sweetberry Pony
any
Year 7
What Merry Goes 'Round Comes Back 'Round
any but Flower Bouquet
Candy Cane
any
Sunshine
Mainsail
Sand Digger
Seaflower
Shoreline
Perfume Puff
any
Princess B'N'G
any
Loving Family
Mommy Bright Bouquet
Mommy Sweet Celebrations
Daddy Sweet Celebrations
Apple Delight (any)
Sparkle Ponies
Star Hopper (either version)
Napper (either version)
Sunspot
Star Dancer
Sky Rocket
Baby Fancy Pants
any
Playtime Baby Brother
any
Windy Wing
Cool Breeze
Flurry
Starry Wings
Baby Ponies and Pretty Pals
any, pony or pal
Year 8
Tropical Pony
Pina Colada
Hula Hula
Tootie Tails
Rainbow Curl
any but Ringlet
Baby Sparkle Ponies
Baby Firefly
Baby Northstar
Year 9
Rockin Beats
guitar brush accessory (any)
Glow 'N' Show
ANY
Baby Rainbow
Baby Sunribbon
Baby Starbow
Baby Ballerina
any
Teeny Tiny
any
Eyelash Princess
either
Year 10
Flower Fantasy
any
Sippin' Soda
any
ice cream float accessory yes please
Colorswirl
any
Paradise Baby
any
Fancy Mermaid
any
Birthday Pony
Birthday Pony
Other identical Birthday Pony
A third Birthday Pony, sure why not
Mail Orders/Specials
Lucky the Stallion
Coat 'n' Tails
Scribbles
Dabble
Rapunzel
Goldilocks
Li'l Tot
White Valentine Baby
Baby Chuck E Cheese
Pearlized Babies
any except Glory
TAF Babies
any of course, obviously well of course
Spike
G2
Sea Breeze
Hip Holly
Flash (with her rollerskates)
Merry Moments
Bright Bramley (with her clothes)
Princess Silver Swirl
Lady Cupcake
G3
Any Dolly Mix ponies
2003
Dazzle Surprise
Moondancer
Autumn Skye
Baby Bellaluna
MIB Wing Song
2004
Starbeam
Savannah Sage
Wondermint
2005
Always & Forever (with wings)
Yours Truly (with hideous pants)
Silver Song
Dress-Up Daywear Shenanigans
Dress-Up Daywear Sweetsong
Island Rainbow
Strawberry Reef (with ugly head)
Toboggan
Ribbons and Bows
Jingle Jangle
2006
Alphabittle
Flower Garland
Tangerine Twinkle
March Daffodil
Rhythm and Rhyme
Sunrise
Let's Go pose Twinkle Twirl
2007
Morning Glory
Daisy Paisley
Aurora Mist
3D Symbol Rarity
Molded-wing Star Catcher
Butter Pop
Lovely Ladybug
Snow'El 2
2008
I have a thousand of all of them
G4
Lily Blossom