I caught the black one whein I was Lv 24, with my seduction skill at Lv 17 or so, it was Lv 18 at that point. That is the weakest Gobbal Warchief you can find, it was all alone, and still it almost killed me. >.<
6 or 7 hours of training with its help later, I was lv 30, has my seduction skill at lv 25, and my Warchief at the level you see in the screenshot.
And here is what he is like now:
It is too bad the inactive one doesn't get experience, so I'll have to catch a new one once I finally got my hands on a Blue Larva Hat.
I'll take on the Royals once I'm sure I can handle them, that is, when I have roughly their level. :3
Seeing this, I'm a little worried though, at what a Royal Gobball might be like: