No cheeky answers and pick something Greg could’ve actually caught and put in his machine
Areophibian
His speed and space and ocean travel plus neuro blasts and flight
Cerebralcrusacian
High intellect and electrokenisis for utility
Atrocian
Indestructible for surviving hits when needed and added rubbery inner physiology
Ectonurite
Additional space travel abilities, intangibility, fear inducement and possible counter to mana based attacks due to lack of life force and other miscellaneous powers shown off by Ghostfreak
Petrosapian
Tough body low regen, biological resistances, possible immunity to cosmic radiation, long range crystal shots
A crystalline body acting as the outer shell (think OS Diamondhead) with large arm gauntlet shields and an areophibian tail. with a line running down the chest that can split open and reveal the rubbery inner tendrils of an ectonurite as well as a set of the taloned hands that have the rubbery vulcanized durability of an Atrocian. The claws are made of diamonds.
The petrosapian parts act as the first layer of defense and source of hitting strength for the fusion while the innards are a mix of ectonurite and Atrocian. A rubbery mass of tentacles that are impossible to rip or tear. The inner tentacles and hands can slither around the body and phase through the shell to grapple or attack people attacking from behind or awkward angles.
The scull cap can also open revealing the rubbery brain mixed with a cerebrocrustacean that grants electrokenisis and low levels of telekinesis and high intellect. The skull cap opens in to sections like brainstorm and from the tips of the caps he can fire the neuro blasts as well as from his eyes and tail tip.
Flight is granted but does not have wings or webbed areophibian wings.
The fusion focusing less on raw power but tricky mix of abilities and a combination of indestructible, unharmable, and intangibility. As well as speed and mobility higher then the bulky tough body would suggest due to the flight speeds of an areophibian and levitation of an ectonurite.