Nearly all of the weaker opponents now have special loot that can boost the stats of your pets! But, they only work on pets in tier 3 or lower! Also, they are untradeable, so they're only for you to use. Have fun leveling your pets up to the higher tiers!
I really want to put the eggs in my pet's TC. Could you make them unable to be transferred through pet trades, so I could? My pet collects eggs to hatch and raise. ; n;