MTG Salvation

Pony deck with an enchantress shell. Goal is to assemble Omniscience + Conflux (ideally with Academy Rector + Diabolic Intent) to tutor and play all the ponies. Enlightened Tutor/Eladamri's Call find Composite Golem, which helps activate Twilight Sparkle's ability. Eternal Witness/Praetor's Counsel allow you to replay Conflux/Composite Golem.

Since four of the ponies don't exist yet, you can try to Conflux for Rarity, _____, Evil Twin, Dack's Duplicate, and Altered Ego instead, and use Composite Golem mana to change their names.

With Omniscience out, you can alternatively try to win by drawing through your deck with enchantress triggers and swinging with the angels from Sigil of the Empty Throne + Temur Ascendancy.

Composite Golem goes well with Nim Deathmantle if you cannot afford omniscience, as said combo grants infinite mana.
Not sure if this would work, but Spy Kit might be your answer. There are also the wish type spells and Fae of Wishes to search for cards from your collection. The question is the definition of “card”. Using the wish cards with As foretold means you would be able to cast cards with no mana cost, be it Living End or hopefully something like Garruk the Slayer. Obviously none of this last part would be tournament legal, but you might be able to argue that MLP cards are still cards and search them with Wishes.

Unfortunately, Spy Kit does not work because the ponies are legendary.