Low float, high float, repulse, and knockdown are all momentary statuses that merely setup a combo. For example one of your ninja may slam an enemy into the ground, which might cause knockdown. When this status exists the game will check your team in order to see if anyone can combo knockdown. You can tell what ninjas combo based on what states their standard & mysteries create and their "chase" abilities. Chase abilities are what's used to decide if that ninja can combo off that hit. I'll use team 7 as an example.
Naruto & his clones knock the enemy up and create low-float -> Sasuke chases low float into repulse -> Sakura chases repulse -> Sasuke chases again with his phoenix fire jutsu since the combo exceeded 10 hits.