We already have one canon IH Giygas and two fanon IH Giygas, and I'll introduce another potential IH Giygas.
NOTE: "BUZZBOUND - Shadows of Giygas (EarthBound's Bad Ending)" by BigSharkZ and "BUZZBOUND - Cursed Earthbound Prequel" by LumpyTouch are different fanworks. Also, "BUZZBOUND - Shadows of Giygas (EarthBound's Bad Ending)" by BigSharkZ contains AI-generated content.
What's the Work?
"BUZZBOUND - Shadows of Giygas (EarthBound's Bad Ending)" is a YouTube video by BigSharkZ. It is also a fan video of "BUZZBOUND - Cursed Earthbound Prequel" by LumpyTouch. In Shadows of Giygas, Buzzbound, a fanmade prequel of Earthbound featuring Buzz Buzz and the corrupted Ness, is presented. However, unlike LumpyTouch's version, Buzz Buzz loses to Giygas in BigSharkZ's version.
Who Are They? What Make Them Heinous?
Giygas is the main antagonist of Buzzbound.
Before the story of this Buzzbound, Giygas successfully consumes Ness. With the power of Ness, Giygas successfully invaded the Earth and turned the Earth into the living hell.
Giygas is responsible for turning the world, including Onett, into the living hell in the timeline where Giygas succeed. While Buzzbound mainly focuses on Onett, the scene in Onett is enough to show how heinous Giygas is. Inhabitants in Onett have been mutated and have their life energy siphoned. The mutated beings would attack any survivors, such as Picky and Buzz Buzz, who comes to the creepy world to find Ness. There are people who are turned into stone. Porky is heavily implied to be mutated into the Neglected Shadow. Picky is infected and eventually chooses to commit suicide to prevent himself from being mutated. Ness' mother and sister are mutated. Paula is killed and her psyche is heavily implied to be shattered before her death. A Starman Prime, one of Giygas' minion, is empowered by Giygas. Then, after encountering many creepy things such as anti-privacy screen and blood-red texts, Buzz Buzz eventually encounters Ness, who has been possessed by Giygas (Ness' psyche is shattered as well) and become Dark Ness. Despite Buzz Buzz's best effort, Dark Ness overwhelms Buzz Buzz, brutally dismembers Buzz Buzz, and siphons its life energy. With Buzz Buzz destroyed, Giygas' invasion becomes more successful, and the Earth fully becomes a living hell. Poo, somehow survived, becomes the possibly only survivor who are capable of fighting and will start his adventure to find the last hope.
Heinous Standards
Giygas easily passes the heinous standard. Giygas is the main antagonist of this Buzzbound. Invading the Earth, mutating or siphoning its inhabitants, torturing at least Ness, Paula, and Buzz Buzz. Even if some of the heinous actions may not be committed by Giygas themselves, these heinous actions are all directly or indirectly an extension of Giygas (e.g. Giygas' corruptt influence) and beneficial to Giygas.
What Makes Them Inconsistent?
This Giygas has potential Insufficient Characterization problem and is possible a Generic Doomsday Villain. While it can be argued that this Giygas have more characterization because this Giygas' more direct appearance, this Giygas suffers from moral agency problem. When Buzz Buzz encounters Dark Ness (aka Giygas after consumed Ness), Starman Prime states that "by allowing [Ness] to merge with Giygas, he turned into a harbinger of destruction. [Ness'] heart is no more, and [Ness'] mind pulses with pure evil intent. [Ness'] essence is no longer bound to Earth; he has become nothing more than a puppet dancing on the strings of cosmic malice." While Starman Prime is telling about this Ness' status, it does heavily impliy that this Giygas has moral agency problem because this Ness is forcefully merged with Giygas and therefore this Ness is technically this Giygas.
Verdict
I vote to weak Yes.