I use them to increase my numbers to connect to Abominable Unchained Soul or Knightmare, or to set up Abyss Dweller if I'm going first
Rockruff takes 20 additional damage from Grass-type attacks
If a set contains cards no cards in the sparkling yellow rarity, the probability of getting a yellow becomes 1/360 + 2/360 = 3/360, assuming the pack has any yellow rarities
Her ETB will reliably draw a lot of cards combined with disguise (or with a lot of ordinary token generators), while her triggered ability ensures all your bears will grow up big and strong like their mama
You can repeat this cycle as long as you have enough mana, and it also works well with mana dorks like Bloom Tender that can generate a lot of mana in a single activation
It sports cards such as "Des Koala", "Des Kangaroo", and "Eucalyptus Mole", all of which reflect his affinity toward such animals, including his favorite card, "Big Koala"