Splatoon only connects once online when it shows the Splatoon splash screen. I know this because once I loaded it and then when I got to the start screen where it shows Inkopolis, I disconnected my router and it still showed the news. Afterwards it said I was offline when I tried to go into the shops or into the Lobby.I thought the offline mean without internet connection. I thought that when callie and marie present the stage Splatoon stay online 100%
Level editing is a bit more sketch, but as long as you don't go from like 1 to 50 I think you'd be good.