The biggest Splatfest ever for Splatoon 3 on Nintendo Switch runs from 13th to 16thSeptember with a three-day festival of music, ink-splashed competition and community fun for players with a Nintendo Switch Online membership. And this time, it’s not just the Anarchy Splatcast hosts Deep Cut who are getting in on the act – all three idol groups from the Splatoon series will perform at the Splatfest while players will try to answer the impossible question, “Which is the most important to you: Past, Present or Future?” The Splatoon 3 – Grand Festival is coming! (Nintendo Switch) trailer shows a glimpse of the festival stages. And across the 72-hour Splatfest, who knows what other surprises are in store?
For newcomers eager to splat, a bundle with the physical version of Splatoon 3, a code for the Splatoon 3 Expansion Pass and a 3-month (90-day) Nintendo Switch Online Individual Membership will be available at retailers and on My Nintendo Store starting 25th July. Plus, on 5th September, two new sets of amiibo figures will be released, one featuring the Squid Sisters and one featuring Off the Hook as they appear in the Splatoon 3 story mode and the paid DLC, Side Order.
Source: Nintendo UK

Is this supposed to be the FinalFest for Splatoon 3…?
If so, they’re really pulling out all the stops, and the theme is actually great- I honestly have to think about which team I’d be on for this one.
It’s definitely final fest just slightly name different dataminers found the file names as finalsand back in May implying that it would be taking place in a dessert like area.
Ok. One more splatfest. I can do it. Had to put it down for a while, got kinda burnt out.
Looking forward to the Splatoon 3 Splatfest. Should be fun to see all the idol groups together. Wondering what surprises they’ll have this time around!
I will miss this. I have been playing video games for 30 years, and this is the first game to keep me this engaged for a full two years.