Have

Grizzly Bears

Giant Growth

Target creature gets +3/+3 until end of turn.

Forest

Wilson, Refined Grizzly

This spell can't be countered.
Vigilance, reach, trample
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Choose a Background (You can have a Background as a second commander.)

Runeclaw Bear

Ayula, Queen Among Bears

Whenever another Bear you control enters, choose one —
• Put two +1/+1 counters on target Bear.
• Target Bear you control fights target creature you don't control.

Werebear

{T}: Add {G}.
Threshold — This creature gets +3/+3 as long as seven or more cards are in your graveyard.

Savage Swipe

Target creature you control gets +2/+2 until end of turn if its power is 2. Then it fights target creature you don't control. (Each deals damage equal to its power to the other.)

Balduvian Bears

Wild Growth

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G}.

Prevent all combat damage that would be dealt this turn.

Mother Bear

{3}{G}{G}, Exile this card from your graveyard: Create two 2/2 green Bear creature tokens. Activate only as a sorcery.

Ayula's Influence

Discard a land card: Create a 2/2 green Bear creature token.

Bear Cub

Yavimaya Gnats

Rhonas's Monument

Green creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature you control gets +2/+2 and gains trample until end of turn.

Explosive Growth

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Target creature gets +2/+2 until end of turn. If this spell was kicked, that creature gets +5/+5 until end of turn instead.