Fireball, like Clobber, is a member of the Baxter Gang (four super powered Australian crims/thugs/bank robbers) and was first seen in Daze as part of a dream Go!Anna was having. Essentially able to generate flames from his body and shoot fireballs – but is too large to be able to fly (in case you were wondering). In true Australian style, he and his fellow Baxter Gang mates got their powers from accidentally drinking radioactive beer.
Gabby is a DNA+ able to breathe fire. She has previously lamented not being able to “cut loose” with her power, so she must be in her element here, so to speak.
Jenna is a Forn demon. The Forn are able to manipulate the elements varying degrees (earth, air/wind, fire, water and metal). It is rare for a Forn to be a master of all and Jenna has previously struggled with most of those categories.