You probably know this already, but it's worth citing.
Float status in the SNES versions of this game can work with a number of other statuses visually..
Image (both versions), Poison, Piggy, Toad, Mini, Jump (kinda), Charging, Parrying, Stop, Reflect/Wall, Hide (probably)
There could be more...
Every other status overrides Float status.. although this excludes Critical status. I'm not entirely sure why.
You can tell if a character is in critical by the inability to perform their command actions while they are "standing up" in mid-air.
It's actually amusing that you can apply Float status onto a dead/stoned character outside of battle.
These issues are corrected in FF4A..