We'll have to wait a bit longer and see how it runs tomorrow night when the update hits. If it is like Ninja Squid though, it will need at least 1 main to counter slightly. Two to three subs and 1 main to counter entirely. I think 1 main Swim Speed may be enough to counter it and bring the Dynamo back up to speed even if not fully counter it. Splatoon decided to be nice last night and gave me a triple Special Charge on my Squid Hairclip (exactly what I was searching for in a piece of gear) so that solves my issue with the Swim Speed. I plan to just switch out my Ink Saver hat for the Hairclip. :)
It's definitely something for us to play around with builds and such to find the right balance.
Whenever I play the Dynamo, I usually stack lots of Quick Respawn, as you trade often or get splatted just before your swing activates. I haven't played Dynamo as much recently, but my current set has 3 Mains and 3 subs of QR stacked. I already have my idea for a build, which involves sacrificing my Backwards Cap (1 main, 2 subs of QR) for my Squid Hairclip, which after one reroll got 3 QR subs. I'll still use the Squid Satin Jacket (QR main & 3 Special Saver subs) and the same shoes, so I'll have 2 mains, 4 subs of QR, 1 main of Swim Speed, 3 subs of SS, and 2 subs of QSJ (my Biker Boots have the 2 x QSJ and 1x QR). I've also got other ideas, like using the Squid Girl shoes and going for 3 QR subs, or purifying them and using the same hat as before. If I use the QR style, I can get the Zekko Black Arrowbands with their 3x Special Saver as an alternative to counter special loss, or if I go for the pure format, I'll go for the Skalop Tenacity hat (or shiny a Tenacity hat for 3x Swim Speed and having the QR Squid Girl shoes).