Afiya Grove

Afiya Grove enters with three +1/+1 counters on it.
At the beginning of your upkeep, move a +1/+1 counter from Afiya Grove onto target creature.
When Afiya Grove has no +1/+1 counters on it, sacrifice it.

Bear Cub

Grizzly Bears

Aim High

Untap target creature. It gets +2/+2 and gains reach until end of turn. (It can block creatures with flying.)

Ashcoat Bear

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

Alpha Authority

Enchant creature
Enchanted creature has hexproof and can't be blocked by more than one creature.

Werebear

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

Balduvian Bears

Forest

Forest Bear

Aether Web

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1, has reach, and can block creatures with shadow as though they didn't have shadow. (Creatures with reach can block creatures with flying.)

Aggressive Urge

Target creature gets +1/+1 until end of turn.
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.