Quick explanation: I've started a playthrough on a map with caves and one of them had a Phanpy Tunnel in it.

There were only one Phanpy and Donphan each, but the Donphan ripped apart one of my Hoppip and the Phanpy destroyed an approaching pirate. Are these always this aggressive or is that only the case when they're spawned from these hives?

The Donphan's aggro range wasn't very large, but my pawns kept fleeinng from it, so I set them to ignore enemies until the Donphan decided to make it personal.