Rarities

Legendary class and legendary traits

only legendary leech monsters have these

Luxury class

Mythical traits only obtained by using uncommon mythical upgrades

Mythical traits only obtained by using common mythical upgrades

Traits obtained through the use of shop items.

Saltwater class/saltwater traits

Usually only saltwater leeches can have these traits, but on rare ocassions or by using special items normal leeches can have them as well.

Pet/Mount/Wild classes

Normal traits anyone can use

Traits that are not listed on the trait sheets, only obtainable through special means.