[Sol Fury]

Entirely possible. The anime has shown that Tiera has certain special abilities. I wouldn't put it past him to outright fight with two mecha stuck back to back - especially since each of the upgraded Gundams embodies some of the abilities of their predecessors.

Arios - jet mode transformation, same as Kyrios
00 - mostly a balanced unit, with an emphasis on speed and melee attacks like Exia. Also has the angelic energy wings inherited from 0 Gundam.
Cherudim - sniper unit same as Dynames. Seems to be the least upgraded so far as I've seen.

That leaves Seravee, the Virtue upgrade. Virtues main abilities were to utilise heavy firepower (Seravee has this) and to switch to a faster combat unit in times of dire need, the Nadleeh. That was done by shedding all the armor. Seravee has shown no sign of actually disengaging armor, but looking at that, it is entirely possible it will launch the rear section, possibly with that face forming the chest and a smaller head coming out of the top.

Of course combining is not out of the question given 00 Gundam has the 0 Riser and Arios seems to have a second mecha that attaches to the rear end of the jet mode.