Halsin, Emerald Archdruid

{1}: Until end of turn, target token you control becomes a green Bear creature with base power and toughness 4/4 in addition to its other colors and types.
Choose a Background (You can have a Background as a second commander.)

Kodama's Reach

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Cultivate

Sol Ring

Awaken the Bear

Target creature gets +3/+3 and gains trample until end of turn.

Bear Down

Destroy target artifact or enchantment. (Then exile this card. You may cast the creature later from exile.)

Stormkeld Vanguard

Stormkeld Vanguard can't be blocked by creatures with power 2 or less.

Stormkeld Vanguard // Bear Down

Owlbear

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

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.)

Bear Umbra

Enchant creature
Enchanted creature gets +2/+2 and has "Whenever this creature attacks, untap all lands you control."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Circle of the Moon Druid

Bear Form — During your turn, Circle of the Moon Druid is a Bear with base power and toughness 4/2. (It loses all other creature types.)

Copper Host Crusher

Trample
Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Runeclaw Bear

Goreclaw, Terror of Qal Sisma

Creature spells you cast with power 4 or greater cost {2} less to cast.
Whenever Goreclaw, Terror of Qal Sisma attacks, each creature you control with power 4 or greater gets +1/+1 and gains trample until end of turn.

Professor of Zoomancy

When Professor of Zoomancy enters, create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life."