Surf over Reflect on Latias is something I actually considered frequently during the playtest. I think it's probably the single best change that could have been made to the team. Aromatherapy is something I really struggled to fit onto my Blissey, but I have to admit that Toxic is primarily for offensive Pokemon immune to TSpikes that set up on it. A Blissey without Toxic is setup bait for Dragonite, Latias (non-Refresh), Gyarados, and Virizion. Plus, random Toxic is really practical for using on the switch if you're expecting a sweeper. As much as I'd like Aromatherapy, my Blissey suffers 4MSS and really can't spare the slots. It's something to consider, though. Also, Tentacruel has really shitty PhysDef and gets rocked by Shadow Claw even uninvested. Even when burned by Scald, I never had trouble muscling through Tentacruel (although, admittedly, I do wish I had Night Shade for reliability, but I love the Shadow Claw OHKO on Starmie and Alakazam).
Lastly, your point about CM Reuniclus is well taken. I would have had trouble with it, but it was incredibly rare in this meta thanks to the offensive nature of most Necturna. People just used TR instead, which this team handles without fail, but which offensive Necturna teams had more trouble with. Because I was basically the only person running stall high on the ladder, no one ran a stallbreaker Reuniclus. This was fortunate for me, although something I'd definitely want to cover if this were continuing. Notably, Necturna takes way too much investment to 2HKO CM Reuniclus with Shadow Claw. I think the better choice in the grand scheme would be to use CB Scizor over Latias, as I noted in the RMT itself. This covers Reuniclus and Terrakion and can do a number to Lucario in a pinch.
Oh, and Karp, ScarfToed is something I toyed with early on. It helps also with my weakness to Trick, but didn't provide the versatility I needed and the physical bulk. I think again, keeping Politoed as-is and going with Scizor > Latias might be the better overall choice.
Thanks for the comments guys! I was glad to playtest Necturna with you!