Balduvian Bears

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.)

Owlbear

Trample
Keen Senses — When Owlbear enters, draw a card.

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.

Exuberant Wolfbear

Whenever Exuberant Wolfbear attacks, you may change the base power and toughness of target Human you control to Exuberant Wolfbear's power and toughness until end of turn.

Dragon-Scarred Bear

Formidable — {1}{G}: Regenerate Dragon-Scarred Bear. Activate only if creatures you control have total power 8 or greater.

Bear Cub

Grizzly Bears

Ashcoat Bear

Flash (You may cast this spell any time you could cast an instant.)

Druid's Familiar

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Druid's Familiar is paired with another creature, each of those creatures gets +2/+2.

Striped Bears

Runeclaw Bear

Werebear

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

Golden Bear

Owlbear Cub

Mama's Coming — Whenever Owlbear Cub attacks a player who controls eight or more lands, look at the top eight cards of your library. You may put a creature card from among them onto the battlefield tapped and attacking that player. Put the rest on the bottom of your library in a random order.

River Bear

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)