Krosan Beast

Threshold — Krosan Beast gets +7/+7 as long as seven or more cards are in your graveyard.

Squirrel Mob

Squirrel Mob gets +1/+1 for each other Squirrel on the battlefield.

Acorn Catapult

{1}, {T}: Acorn Catapult deals 1 damage to any target. That permanent's controller or that player creates a 1/1 green Squirrel creature token.

Changeling Titan

Changeling (This card is every creature type.)
Champion a creature (When this enters, sacrifice it unless you exile another creature you control. When this leaves the battlefield, that card returns to the battlefield.)

Squirrel Wrangler

{1}{G}, Sacrifice a land: Create two 1/1 green Squirrel creature tokens.
{1}{G}, Sacrifice a land: Squirrel creatures get +1/+1 until end of turn.

Chatter of the Squirrel

Create a 1/1 green Squirrel creature token.
Flashback {1}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Birthing Boughs

{4}, {T}: Create a 2/2 colorless Shapeshifter creature token with changeling. (It has every creature type.)

Game-Trail Changeling

Changeling (This card is every creature type.)
Trample

Zoologist

{3}{G}, {T}: Reveal the top card of your library. If it's a creature card, put it onto the battlefield. Otherwise, put it into your graveyard.

Druid's Call

Enchant creature
Whenever enchanted creature is dealt damage, its controller creates that many 1/1 green Squirrel creature tokens.

Webweaver Changeling

Changeling (This card is every creature type.)
Reach
When Webweaver Changeling enters, if there are three or more creature cards in your graveyard, you gain 5 life.

Nut Collector

At the beginning of your upkeep, you may create a 1/1 green Squirrel creature token.
Threshold — All Squirrels get +2/+2 as long as seven or more cards are in your graveyard.

Acorn Harvest

Create two 1/1 green Squirrel creature tokens.
Flashback—{1}{G}, Pay 3 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Chameleon Colossus

Changeling (This card is every creature type.)
Protection from black
{2}{G}{G}: Chameleon Colossus gets +X/+X until end of turn, where X is its power.

Liege of the Hollows

When Liege of the Hollows dies, each player may pay any amount of mana. Then each player creates a number of 1/1 green Squirrel creature tokens equal to the amount of mana they paid this way.

Ghalta, Primal Hunger

This spell costs {X} less to cast, where X is the total power of creatures you control.
Trample

Deep Forest Hermit

Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Deep Forest Hermit enters, create four 1/1 green Squirrel creature tokens.
Squirrels you control get +1/+1.

Squirrel Nest

Enchant land
Enchanted land has "{T}: Create a 1/1 green Squirrel creature token."

Deranged Hermit

Echo {3}{G}{G} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Deranged Hermit enters, create four 1/1 green Squirrel creature tokens.
Squirrel creatures get +1/+1.