Who is their TRUE nemesis?

Every villain has a nemesis - some hero who has a particular connection to that villain, and who does extra damage to them. But sometimes, the official nemesis isn't very well suited to exploiting the villain's weaknesses. Meanwhile, some OTHER hero is well-equipped to hit the villain where it hurts most. This is my attempt to gather together all those heroes, those true arch nemeses who really keep the villains awake at night.

Baron Blade: Visionary - Blade's best weapon is his countdown timer, and the Visionary is the only one who can reset it. Whether it's two cards at a time with Suggestion, or all at once with Brain Burn, the Visionary can reverse the polarity of the Terralunar Impulsion Beam and put the moon back in place, buying the heroes precious time to take down the Baron. (I wonder how it feels on the Baron's end? "I was this close to pulling the moon into the earth! What possessed me to deactivate the Impulsion Beam now?!")

GloomWeaver: Parse - Gloomy is vulnerable to having his relics trashed, and Parse is uniquely good at trashing the enemy's best cards. Extrasensory Awareness can discard relics while also preventing Gloomy from resurrecting them with Vast Following, and Buffer Overflow can zap relics if they ever get played. Buffer Overflow is noteworthy for being able to get rid of indestructible cards, not before they are played, but at the moment they're played. Defeating Ultimate GloomWeaver without ever dealing him any damage is a pleasure that Parse can deliver more conveniently than anyone else. (What is Parse's religious affiliation? Judging by how well she shuts down GloomWeaver, I'm guessing anti-theist.)

Plague Rat: Mister Fixer - I almost gave this one to Ra, whose famous combination of Flesh of the Sun God and Imbued Fire negates all the self-harm that Plague Rat inflicts on the heroes, but if you want to go beyond preventing self-harm and turn it into harming the enemy, you need Fixer and his trusty Jack Handle. One copy of Infection in the right place, plus three copies of Afflicted Frenzy, mean that Mr. Fixer can get up to four free attacks on his turn, and everything that would make him hit himself harder makes him hit Plague Rat harder. (Any good martial artist knows how to redirect damage away from themself, but you really have to admire a man who can redirect infectious disease away from himself.)

Kaargra Warfang: Stuntman - Sky-Scraper never really wanted the gladiator life, but Stuntman can't get enough of it. Get him into the arena and he owns the place, scoring points and winning titles left and right. His Action Hero variant seems to be especially good at stealing the crowd's hearts and knocking Kaargra off her throne. He just can't help himself; he always puts on a blockbuster performance. (I should note that I'm not quite sure WHY Stuntman is so good at ruling the arena. He seems to be better than everyone else, which is fitting, given his theme, but just what is it that makes him so good?)

The Chairman: Haka - The usefulness of Savage Mana makes Haka well-suited to beat a number of villains, but I picked the Chairman because no other villain is so good at getting every last card out of their trash as the Chairman is, and no hero is as good at locking up cards as Haka is. (Haka can even eat the Chairman. Being beaten is one thing, but being absorbed into your enemy, to later be recycled into a super attack? That's got to sting.)

Citizen Hammer: Ra - Flesh of the Sun God. Enough said.

This is, alas, only a partial list; I need your help to finish it! Can you help me list which hero each villain fears most? Redditors assemble!