Photoners started multiple planetary wars against other multiple planetary races in every corner of the universe. They even forced Makians to deliberately kill themselves by making Gigantes because how relentless Photoners are. Shiva and her gang aren't the only adversaries wanting to wipe out the Photoner legacy.
Appearance wise, Giganti have a dragon-like body structure and look very mechanical, and is revealed earlier in the game that they have a cockpit-like seat on the top of their head, suggesting that Giganti were artificially built.
Sound familiar?