I like the azure whelp, though it's very much a glass cannon compared to some other pets. Usually I use a Magical Crawdad and Darkmoon Zeppelin to handle the more tanky bits.
The whelp has a basic attack strong against magic or critters, and critters are very common. Arcane storm is useful against stunning pets, clearing up weather effects and doing some aoe damage.
The third slot has big hitters with Ice Tomb and Surge of Power. Ice Tomb is handy as it does a ton of damage and stuns. Surge of Power does huge damage, but requires 2 round of recharge. It's best to use Surge as a finisher, and it's especially powerful when combined with the 50% extra damage dragonkin do after reducing an enemy below 25%. This does proc even if you kill the enemy, so you can sometimes do some silly damage to the next pet to come along. You can one shot most flying pets this way, and nearly kill most others. The proc is not limited to the pet you brought under 25%, it buffs the dragon in general.