BlackMax on Allspark has done some quick translations of the bio blurbs from the TakaraTomy Mall page for Grand Galvatron. Giving basic background and origin info for the involved characters, there's not a lot of surprises to be found, but taken together they offer some context to the grouping of these characters as a combiner team. We've got the translations quoted below, so keep reading to have a look!
Emperor of Destruction Galvatron's loyal Air Staff Officer. Transforms into a Sci-Fi jet. Receiving a revelation from the dead Galvatron, Cyclonus takes Galvatron's spirit into his body and reformats himself into a new combination-capable "scramble body". Using the power of the Interstellar Emperor Unicron, Cyclonus summons from other dimensions warriors bearing strong malice and evil power. Using the combined energy of their malice, they seek Galvatron's complete resurrection!
Former "Number 2" of the Destron Army; known by all as a traitor. Transforms into a jet fighter. Wandering space as a being of pure spirit energy, Starscream was resurrected by the power of Unicron and sealed into a half-living-half-dead, insubstantial "ghost body". Now, his insubstantial form radiates the malicious energy generated by his hatred of his murderer, Galvatron. He appears to be cooperating with Cyclonus and Galvatron, to whom he owes his resurrection, but his true nature remains unclear.
Curse Armada Thrust:
Destron warrior from another dimension, he is known as a cool-headed strategist. Transforms into a jet fighter. Once crushed to death during Unicron's transformation, Thrust harbors complicated feelings towards being summoned and resurrected by the Unicron of another dimension. It seems like he secretly plots to somehow use the revived "Grand Galvatron" formed, in part, by his new "scramble body" to get his revenge on Unicron.
(Translator's note appears in italics)
Zombie War Breakdown:
Decepticon (yes, it specifically calls him a Decepticon) warrior from another dimension, he is adept at destruction. Transforms into an off-road car. Killed by his comrades and forced to suffer the use of his corpse by human, Breakdown's incredible malice would not allow him to die. Instead, he roamed the earth as a zombie until he was summoned by the Unicron of another dimension. Resurrected in a new "scramble body", Breakdown faithfully obeys the orders of his new master. However, in his deepest thoughts he dreams of reuniting with his former partner, and secretly longs to return to his original dimension.
Wanders the space between dimensions after being separated from his comrades in the heat of battle, he was originally a Cybertron warrior. Transforms into a 6-wheeled armored vehicle. Roller's spirit was destroyed by absolute solitude while awaiting rescue by his sole comrade. Believing himself abandoned by his trusted comrade, he became ruled by despair and self-condemnation to the point where he eventually carried strong malicious energy. That energy was sensed by Unicron, who brought him to this world. His memory is patchy due to his long wanderings, but he still bears an incredible hatred for the symbol of the Cybertrons: Supreme Commander Convoy.