Ascended Meme: "I'M IN A FUCKING WHEELCHAIR" became very popular to say in reference to Gold once the mod came out, owing to his lack of arms or legs.
Animalistic Abomination: Hypno is already pretty odd-looking with several animal and human qualities, but this mod takes it a step further with his form in "Left Unchecked", where his head detaches from his body and gains a large Ghostly Gape.
has a lack of context to its encounter with Boyfriend, so we dont really know what it wants.
Animal Gender-Bender: The Hypno present in this mod is male and has a very deep voice to match, but its neck fur is long and straight, a trait present only in female Hypno (males' neck fur is shorter and scruffier in comparison).
This could've been due to both of their deaths early on in the fic and game, but he also uses the similarly-deceased Away the Celebi.
Adapted Out: Gold uses most of the Pokémon he owns in Pokémon Lost Silver, but noticeably never utilizes Hurry the Cyndaquil or Please! the Typhlosion from the hidden route.
Here, Hypno is a single entity that actively hunts and successfully kidnaps Boyfriend and Girlfriend For the Evulz. In the regular series, Hypno are a species of Pokémon that range from neutral to downright helpful, with them nearly never using its sleep inducing powers to harm people (only feasting on their dreams) and only one known incident of a child kidnapping.
Adaptational Villainy: This occurs with Hypno due to being based on Hypno's Lullaby.
Here it uses its Glitch Entity powers to their fullest, moving the notes all around the screen, especially on Hell mode.
In Red and Blue, while Missingno had extremely high physical attack, it was a Glass Cannon that didn't have the speed nor moveset to utilize it.
This Hypno? An Eldritch Abomination that Mind Rapes people to death and successfully kidnaps a powerful demon like Girlfriend.
Canon Hypno? A Pokémon with subpar stats (which was only somewhat powerful back in time of Pokémon Red and Blue before the Special split and due to the general overpoweredness of the Psychic type, and was outclassed even back then).
In "Insomnia", his face is perpetually framed in shadow with his eyes hidden, if they are present at all, and most of his poses when singing seem to imply that he's in quite a heavy state of pain.
A downplayed example, but in the Hidden Route of the Lost Silver fangame, Silver looks more or less the same as normal, albeit with his eyes missing.
Its depiction in the mod shows all of its organs.
In Pokémon Lost Silver, the sprite of Gold's Celebi was simply cut in half with no gore.
The mod takes this a step further by instead having his limbs being violently torn from his body (justifiable, as this is quite a common depiction of Golds condition among fan works related to the original story), his eyes missing from their sockets entirely, and adding a giant visible heart and the ability to stretch his face beyond normal possibility.
In Pokémon Lost Silver, Gold's sprite limits him to having his arms and legs neatly removed and Tears of Blood coming from his eyes, but otherwise he looked more or less the same as he did in life.
Interestingly, a pair of teaser images posted to Banbud's twitter indicates that Hypno was once closer to its canon counterpart and changed into what it is now. Here, it's become a lot larger and its head is almost tearing itself from its neck in half of its animations, and the form it takes in "Left Unchecked" is rife with Body Horror, featuring its levitating head ripped off of its body and Phlegmings made from its own flesh.
Hypno in the original Pokémon games wasn't too scary to look at - a little creepy at worst - and its powers were limited to basic Psychic Powers and hypnosis.
Neither of Gold's or Missingno's Hell mode additions really make sense (Hypno's Hypno Pendulum appears in Monochrome without a source, and Missingno was removed when Unown was introduced), but they still make their levels harder than ever.
Even in Hell difficulty, Hypno's pendulum doesn't work that quickly, as to be a bit more lenient on the player.
Quite a few of Hypno's Pokédex entries mention that it can put its victims to sleep in 3 seconds.