The users are an "empowered badass normal", starting out as a non-powered entity who can take on superpowered beings and keep up with them through either intelligence, combat training, pragmatism, being prepared for any eventuality, wielding advanced technology and weaponry, or a mix of all five, and then managing to get superpowers of their own. Combined with their per-existing training and experience, this makes them a force to be reckoned with.
Oliver Queen (Arrowverse) was one of the deadliest fighters in the multiverse to even defeat various meta-humans and near-enhanced humans long before he gained
Light Magic...
...and before he became the Spectre.
Even before he revived super strength, Ricardo Diaz (Arrow) was a very powerful crime lord who trained himself in combat and is one of the few opponents who can fight Oliver to a standstill in hand-to-hand combat, despite the lateral being trained by the League of Assassins.
Eren Yeager (Attack on Titan) graduated 5th in his military class through sheer persistence and was noted to be one of the best at hand-to-hand-combat before manifesting his
Titan Shifter powers.
Even before he gained
airbending abilities, Zaheer (Avatar: The Legend of Korra) was an incredibly skilled martial artist.
Already a master swordsman and military strategist, Griffith (Berserk) became even deadlier when he became the
causality-controlling demon lord Femto.
Even before manifesting his Fullbringer powers, Yasutora Sado (Bleach) possessed incredible strength, beating down a Hollow using a telephone pole as a bludgeon.
Even before manifesting magical powers, Sakura Kinomoto (Cardcaptor Sakura) was a master athlete at peak physical condition.
Already a genius at peak physical condition, Batman (DC Comics) has at different points and in different continuities, gained superpowers either temporarily or permanently, such as becoming a Green Lantern...
...or the Devastator via Doomsday Virus exposure.
Videl (Dragon Ball Z) was already a trained martial artist at peak condition before learning flight and Ki control from Gohan.
Already a trained martial artist at peak condition, Ling Yao (Fullmetal Alchemist) became even deadlier upon becoming the second Greed.
Even before his Conduit gene
manifested, Cole MacGrath (Infamous) was an athlete at peak condition who could perform parkour with ease.
Henry Hart (Henry Danger) was a skilled fighter who temporarily gained
indestructibility for 2 days but at a cost of breathing fire when he laughs...
...gained his second superpower
super-fast reflexes for 2 years from breathing in the poisonous fumes of a South African Bush Lizard and a Black Shag Spider...
Drex (Henry Danger) was a skilled fighter to even almost destroy Captain Man in a fist fight and also easily defeated Kid Danger before he gained super-fast reflexes...
...after becoming indestructible, he not only gained a lizard-like hand but also became an equal rival for Captain Man and his sidekick Kid Danger.
Nya (Lego Ninjago: Masters of Spinjitzu) was a genius inventor and a talented martial artist even before she discovered that she is the current elemental Master of Water.
Eddie Brock (Marvel Comics) was a man at peak physical condition...
...which was added onto when he became host to the Venom symbiote.
Even before being experimented on by Weapon X, Deadpool (Marvel Comics) was a highly trained mercenary and assassin.
Even before his
Cybernetic Enhancement, Jax (Mortal Kombat) was regarded as the strongest man in Earthrealm, able to match a Shokan like Kintaro in single combat.
Even before his infection with the Blacklight virus, James Heller (Prototype 2) was a
military sergeant...
...capable of killing a Brawler Hunter with nothing but a knife...
...and briefly standing up to Alex Mercer and surviving hits from him.
Albert Wesker (Resident Evil series) was a master martial artist and marksman before becoming a viral transhuman capable of punching through walls, dodging bullets and tanking RPG explosions.
Even before being infected and enhanced by the
Mold, Ethan Winters (Resident Evil), despite his lack of formal training, was able to competently handle guns, remain conscious after being thrown through a wooden wall, and fend off his infected wife Mia despite losing his left hand.
Before becoming a Knight of Hell with all the power that came with it, Dean Winchester (Supernatural) was a monster hunter with years of combat experience.
Even before April knew and start to use her psychic powers (Teenage Mutant Ninja Turtles 2012 TV series), she was already well skilled in ninjutsu to fight various superpowered beings.
Even before his mutation into the Super Shredder, Oroku Saki/Shredder (Teenage Mutant Ninja Turtles 2012 TV series) was a ninjutsu master with decades of experience.
Even before he drank the
Heart-Shaped Herb, Killmonger (Marvel Cinematic Universe) was an extremely skilled and formidable hand-to-hand combatant and martial artist who easily defeated his cousin in their first duel.
Before eating his late brother, Portgas D. Ace's Flame Flame Fruit, Sabo (One Piece) was a master martial artist in Ryūsōken and a powerful Haki user.
Carmine Prime (Under Night In-Birth) managed to defeat an In-Birth before he even acquired his own powers.
Already a master martial artist and weapons user, Alice (Resident Evil) became even deadlier upon being infected and enhanced by the T-virus...
...enabling her to match and defeat Nemesis in hand-to-hand combat.
Bucky Barnes/Winter Solider (Marvel Cinematic Universe) was a skilled soldier before he was injected with the Super Soldier Serum and later gained a bionic arm.
Already a master martial artist and tactician, Slade (Teen Titans) became even deadlier after being bestowed demonic powers by Trigon.
Marc Spector (Marvel Comics) was a skilled Marine Soldier/Mercenary long before he became Khonsu's Moon Knight, and even afterward he still manages to win fights.
While being in the Resistance, Finn (Star Wars) became promoted to General while being an expert at blasters...
...and melee weapons like a lightsaber and a Z6 riot baton. As time went on Finn discovered his Force-sensitivity.
Sabine Wren (Star Wars) was a highly capable
Mandalorian skilled in various weapons, including a lightsaber. After coming to terms with her issues, Sabine learned to unlock her dormant Force-sensitivity.
Trained in martial arts by Leo Thomas, Che Heart (Ordeal) was able to fight toe to toe with Kimyos without any powers...
...After Leo Thomas's death,
Illios was passed on to him and he became even more powerful and was able to take on very powerful opponents.