Hi, I'm going to go diving in the waters near Undella Town in a week or so to go to the Abyssal Ruins as part of an archaeology team from the museum in Nacrene. We've got Devon scuba gear and Aqua suits, and we know how to swim and dive, well, at least most of us do. Is that sufficient to excavate without a water Pokemon? And is there anything we need to know about the local ecosystem and environment? I heard there's wild Tirtouga out there. Thanks for your reply
Frankly, I'm not sure what's left to excavate in the Ruins; as it was open to the public until fairly recently, expect a decent amount of trainer 'relics'. If you're looking to do some heavy-duty excavation, bring... shovels? I'm not actually sure what you would use to dig into walls.
Watch out for the water torrents. They're infamous for dragging people up and out of the Ruins very violently; and though there's been very few injuries relating to it, it's still something to keep an eye out for. There's some rumors that it's the ghost of former kings keeping those disrespectful out, but I'm not sure how accurate that it.
There are.. Absolutely no wild Tirtouga. Since they've been extinct for a 'hundred million years' (thanks pokedex) they only exist in the hands of researchers and the Pokeballs of trainers. Even if there were, they'd steer clear of people as people would be unfamiliar to them. However, there are Frillish and Jellicent, and a lot of those. I would recommend bringing a Pokemon that can breath underwater as backup and protection; such as Sharpedo, Basculin, Octillary, or really any fast-swimming hard-hitting Water type.
Good luck on your dive! And Undella is a beautiful city to touch base in.