Owlbear Cub

Mama's Coming — Whenever this creature 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.

Sol Ring

Kudo, King Among Bears

Other creatures have base power and toughness 2/2 and are Bears in addition to their other types.

Elesh Norn, Grand Cenobite

Vigilance
Other creatures you control get +2/+2.
Creatures your opponents control get -2/-2.

Flowering of the White Tree

Legendary creatures you control get +2/+1 and have ward {1}.
Nonlegendary creatures you control get +1/+1.

Rampaging Yao Guai

Vigilance, trample
This creature enters with X +1/+1 counters on it.
When this creature enters, destroy any number of target artifacts and/or enchantments with total mana value X or less.

Worldly Tutor

Search your library for a creature card, reveal it, then shuffle and put the card on top.

Balduvian Bears

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 this creature is paired with another creature, each of those creatures gets +2/+2.

Finale of Devastation

Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle. If X is 10 or more, creatures you control get +X/+X and gain haste until end of 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.

Runeclaw Bear

Sylvan Tutor

Search your library for a creature card, reveal it, then shuffle and put that card on top.

Grizzly Bears

Reverence

Creatures with power 2 or less can't attack you.

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.)

Werebear

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

Survival of the Fittest

{G}, Discard a creature card: Search your library for a creature card, reveal that card, put it into your hand, then shuffle.

Evercoat Ursine

Trample
Hideaway 3, hideaway 3 (When this creature enters, look at the top three cards of your library, exile one face down, then put the rest on the bottom in a random order. Then do it again.)
Whenever this creature deals combat damage to a player, if there are cards exiled with it, you may play one of them without paying its mana cost.

Beastmaster Ascension

Whenever a creature you control attacks, you may put a quest counter on this enchantment.
As long as this enchantment has seven or more quest counters on it, creatures you control get +5/+5.

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.

Ashcoat Bear

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

Bear Cub

Ulvenwald Bear

Morbid — When this creature enters, if a creature died this turn, put two +1/+1 counters on target creature.

Ursine Monstrosity

Trample
At the beginning of combat on your turn, mill a card and choose an opponent at random. This creature attacks that player this combat if able. Until end of turn, this creature gains indestructible and gets +1/+1 for each card type among cards in your graveyard.