They were drones in Masterforce and I think the Universe 1 comics

 

They'd really have different personalities from their Decepticon versions, seeing as Snaptrap is a ruthless commander and Tentakil is pretty much a serial killer. I think the only personalities that could stay would be Nautilator (proto-Zoidberg) and Skalor (slob)

 

If the Seacons were Autobots, Seaspray wouldn't feel so lonely.  

 

their autobot counterparts would be captain planet villains.

 

No, it would still work. They would just be serial killers of Decepticons.
Hey, what works for the Dinobots and the Wreckers...

 

They'd be even more "oh, not those guys" than the Wreckers would be  

 

Clearly, seeing as Snaptrap has gained the nickname "The Butcher of the Bogs" during the war, and Tentakil's TFWiki bio is just dripping with slightly creepy serial killer vibes.

 

I always have Devy's Autobot counterpart as Raiden.
There were initially way more Autobots than Decepticons in G1, so having more of the combiner teams as Decepticons evens things up a bit for me.

 

If we wanted an Autobot sea creature counterpart team, maybe we could go with more majestic rather than menacing sealife. A dolphin, humpback whale, sea otter, leafy sea dragon, angelfish, leatherback turtle, and maybe some kind of graceful looking jellyfish, and maybe a hammerhead so the good guys could have a shark as well, for instance.

 

but dolphins terrorize other animals, killing and raping for fun

 

True. And I would rather have a villainous dolphin, but considering that this was Hasbro in the eighties they probably would have gone more for the public perception of dolphins as cute and friendly than the actual scientific fact.

 

Agreed. I was recently thinking about this because there actually is a Decepticon fembot dolphin apparently and i thought that was pretty awesome for exactly the above stated reason.

 

Thinking about this topic some more, I think the Autobot version would probably be the cutest and least powerful of all the combiners.

Seacons = snapping turtle, crab (or lobster), shark, manta ray (or sting ray), piranha, and octopus.

I'd imagine the Autobot equivalent might be:
goldfish, dolphin, jellyfish, sea horse, manatee, and maybe a beluga whale.

 

There's an existing Decepticon dolphin femmebot? Anyone have a wiki link?

Edit: Nevermind, I found her. NAVI-KO.