I have wanted to try and make a beast tamer for a long time but I wanted it to be balanced and interesting. This is what I eventualy settled on

Beast tamer

While at an outpost he produces 1 tamed squid every 24 hours. This squid can be launched like a sub and cannot carry drillers or specialists. The squids do not receive bonuses from global effects. If engaged in sub to sub combat the squid is concidered to have 10 drillers. When it reaches an opponents outpost it laches on to the side. This outpost cannot charge thier shield. Your opponent can use 10 drillers to remove the squid (much like drilling a mine).

Any thoughts about functionality or balance?

Would require a bunch of UI changes. Display number of squids at your base, separate means of launching them, new art for the squidsub, indicator that a squid is interfering with shields, option to remove it, etc.

Some ways to solve this: Squids are Specialists in their own right. In sub to sub combat, the Squid would destroy 10 drillers (with a low combat priority, probably 7), but is itself destroyed in the process. When attacking an outpost, the Squid wouldn't destroy drillers, but would stop shields from recharging for 12 hours.

That way you don't need any UI changes.

Yah I could see it working like that. It could also work like a hire system like the queen has. Every hire cycle he hires 1 squid which looks just like a specialist. It's symbol could be a tentacle. He could be on a sub only if there are no drillers or specialists. Yah UI is always tough to keep consistent.

I'm not half sure if this is serious
I agree with chariot rider that this could be a specialist by itself, but it wold add unnecessary complexity to the game, and too many additions.