The connecting record
shownMob Psycho 100 · vol. 12, ch. 89
Shigeo Kageyama beat Katsuya Serizawa in Mob Psycho 100.
Won over rather than knocked out: Serizawa stops fighting and turns against Toichiro.
What each of them is ranked on
The winner · Shigeo Kageyama · rank 1
Mob
Choked unconscious by Teru, he broke Teru's barrier and lifted the wreck of Black Vinegar Middle School above the clouds; awake again at 100% Sadness, he put the building back. Inside Mogami's mindscape, with his mental body destroyed, he erased the spirit army and the world it lived in. Hit by a car on his way to confess to Tsubomi, he walked across Seasoning City as a storm while Teru, Sho and Toichiro Suzuki tried to stop him, absorbed the blast father and son fired together, and arrived to be turned down.
shownMob Psycho 100 · vol. 1, ch. 8
At 100% Rage, slices off all of Dimple's limbs and exorcises him with a tap to the forehead.
shownMob Psycho 100 · vol. 3, ch. 18
Unconscious at ???%, breaks Teru's barrier and lifts the school's rubble into the sky.
shownMob Psycho 100 · vol. 3, ch. 18
At 100% Sadness, reassembles Black Vinegar Middle School.
All 10 citations
shownMob Psycho 100 · vol. 9, ch. 67
At ???%, absorbs Mogami's spirits and destroys the mental world, freeing Minori.
shownMob Psycho 100 · vol. 12, ch. 90
Lifts the Seasoning City Culture Tower into the sky to fight Toichiro away from the others.
shownMob Psycho 100 · vol. 12, ch. 90
Draws Toichiro's overloaded energy into himself inside a barrier and survives the explosion.
shownMob Psycho 100 · vol. 14, ch. 97
At 100%, spends the rest of his power in one blast, then walks to Dimple to talk.
shownMob Psycho 100 · vol. 16, ch. 100
At ???%, overwhelms Toichiro and absorbs the Charge Bomb he and Sho fire together.
shownMob Psycho 100 · vol. 16, ch. 100
Tsubomi turns down his confession.
shownMob Psycho 100 (anime) · S01E05
Teru and the rubble of the school are carried above the clouds.
Beaten · Katsuya Serizawa · rank 4
The Ultimate 5 — Toichiro's bodyguard
Blasted Joseph, the government's double agent, out of a window when the plot against Toichiro was exposed, and later stopped Sho's Charge Bomb — months of stored energy — before it reached his boss. On the tower stairs he fought Mob with his umbrella as weapon and shield until Mob, at 100% Friendship, sent his own energy into him and his memories of friendship with it, and won him over. Later, while Serizawa shielded Reigen with the umbrella, Toichiro shredded it with blast after blast and drained him. In the ???% storm he shielded Reigen until his own power began to drain, and turned back.
statedMob Psycho 100 · vol. 10, ch. 81
Toichiro tells Joseph that Serizawa is the strongest of the Ultimate 5.
shownMob Psycho 100 · vol. 10, ch. 81
Breaks free of Joseph's smoke and blasts him out of the window.
shownMob Psycho 100 · vol. 11, ch. 88
Blocks Sho's Charge Bomb aimed at Toichiro.
All 6 citations
shownMob Psycho 100 · vol. 12, ch. 89
Mob, at 100% Friendship, sends his energy and his memories of friendship into him.
shownMob Psycho 100 · vol. 16, ch. 100
Shields Reigen with his umbrella inside the storm until his power is drained and he retreats.
shownMob Psycho 100 (anime) · S02E12
Has an electric anxiety attack when Dimple takes his umbrella.
What this does not settle
One fight in one work. It is the only result the record gives between these two, and it is evidence about that meeting and nothing wider — not a general matchup, not a rematch, and not a ranking of its own.
The ladder above it is argued from everything either of them has been shown doing; this page is argued from one citation.
Where the two disagree, the disagreement is the point, and it stays visible rather than being resolved by whichever of them happens to be on this page.