Princess Celestia Synergies: "A Mixed Bag of Beans"

Princess Celestia has a wide assortment of potentials.

Dismiss Friends & Resources:
The Horror! The Horror! (event)

Liza Doolets (Friend)

Manny Roar (Friend and Critter - see below)

Anything I Can Do To Help? (event)

Sunset Shimmer (troublemaker)

Prince Blueblood (troublemaker)

These cards can collectively allow you to diminish your opponent's Friends and Resources.

Back from the Dead!:
Rarity, Nest Weaver (Friend) x2

In addition to her (bonus) ability of Inspired, this card allows you to play a card from your discard pile, as does Foggy Fleece (Friend) x2

Blockade!:
Golden Gavel, Fast Talker (Friend) x3

Timberwolf (troublemaker) x2

These two cards together on a problem create a brutal blockade for your opponent, costing them +3 AT to  play a Friend to the problem or +1 to move a Character to that problem.

Power-up!:
More or less, this is Fluttershy's ability with Caretaker and Critter Friends
Lemon Hearts (Friend)

Fluttershy, Animal Team (Friend) x2

supported by an assortment of Critters: House Mouse, Blue Jay, & Winona.
Eagle, Soaring Raptor (x2) Raccoon, Scrounger (x2)

make good additions because of their abilities to move easily and/or cheaply.

And finally Doctor Horse, M.D. (Friend) x3 round out this section of power-ups nicely.

Power-ups to meet Requirements:

Initially it might seem that there are a fair amount of secondary colour (Diamond - white) cards that could prove difficult to get into play. However, these following cards are awesome at powering up for the Main Phase in order to get those pesky requirements met and into play!

Coco Pommel, Fashion Apprentice (Friend)

Octavia, Star Cellist (Friend) x3

All have the ability power up during the Main Phase to meet requirements.
Octavia, Star Cellist should be accompanied by Private Party (Resource) x2.

It should be noted that  Resources attached to Friends at Home can be used for Octavia, Star Cellist's activated ability to power up. (For example, if a Friend at home has Marvelous Chapeau attached to it, Octavia, Star Cellist can still exhaust it and power up!)

Which brings us to
Accessories!
Attitude and Pizzazz! (Problem) x2

Marvelous Chapeau (Resource) x2

Chic Beret (Resource) x2 (This resource will also come into use when meeting requirements for Diamond (white) cards! Bonus!)

Although the Celestia deck may never be able to play all these strategies at once, there's no reason why it can't be extremely versatile and toggle back and forth, never letting your opponent know where you're going!