For elementals I completely agree on the phoenix hatchling, he's not exactly devastating (unless against mechs) but is pretty good at outlasting stuff while immo helps grind it down.
For dragonkin, I'm quite liking the azure whelp even if just for how I use surge of power as a kamikaze attack
In the tamer fights, multiple times he's been my last pet alive while the tamer still has a pet in reserve. He gets the kill on the second pet (claw is great vs critters) and activates the dragonkin racial of +50% damage for the opening shot on the last pet then you hit surge of power and combined with the racial it can be a 1 shot. Even used in the same way when not your last pet but about to die, a suicide surge can tear a fresh opponent down to low health for the next pet to finish off.