Floppers are the weakest type of Slugs. Their element is unknown. They are very lazy. They can shoot a trail of smoke behind them like a Flatulorhinkus. They don't transform but they are useful in a pinch such as when you don't have a Slug. Upon contact, Floppers produce a splat of slime. Eli has one named Noodle that he uses in the episode "Roboslugs". One popular use for Floppers is accuracy training or sparring, as it can't actually hurt an opponent.
A ghouled version of Flopper has not yet been seen in the show.
They can also be used just to shoot in case you need to block someone's blaster to backfire it, or just to push another slug out of the way. There can be many uses for a Flopper.
Stretching: As seen in a Slugisode, Floppers can be stretch into useful things like tripwire, or to tie someone or something.
Slippery: As seen in a slugisode, Floppers are extremely slippery, so you can slip someone up by throwing a Flopper in their way so they slip and fall.
Eli says,"All slugs are useful. Even Floppers." in "The World Beneath Our Feet part 1", to Pronto when he was practising against Kord.
'Flopper' is sometimes used as a catch-all phrase for any slug percieved to be useless in combat.
In "The Journey Home" it seems that many slugs take offense to being called a Flopper.