I played through story mode on what I think was the easiest level and it was a breeze. I think in a fluke I once lost two lives on one level but it was rare I even lost one. And in story mode, you can just retry the level if you completely fail.
Haven’t tried arcade, that’s the mode where you’re playing through it all in one shot and if you run out of lives it’s game over, but it’s probably almost as easy given how few lives I lost. I’m not entirely sure how the very minor “upgrade” system works in arcade. In story mode, on a per character basis you gradually unlock a couple extra HP, the ability to bank up to 3 special attacks, and some special attack variations. I don’t know if those upgrades are just present from the start in arcade, not present at all, or are still gradually unlocked in the play through.