Confirms the ladder
The higher-ranked entity killed the lower-ranked one. Record and ladder agree.
This is the rare Dragon Ball death that holds, and the ladder is already arranged as though it did. Fifth killed tenth, which is the order the ranking predicts, so nothing needs revising — but the manner is worth stating, because it is the franchise's whole economy in one move. He does not out-hit the thing. He is stalled for by two other fighters while a planet hands him its energy, and the shot lands because somebody else bought the seconds. Note also what did *not* happen: the death was never wished away. Kid Buu is reincarnated as a different person entirely, which leaves the original dead and the record intact — unusual enough here to be worth marking.
Son Goku killed Kid Buu in Dragon Ball Z.shown
stalled by Vegeta and a freed Fat Buu first; the bomb was made of energy borrowed from a planet
Fights Jiren in ultra instinct in the tournament's final stage. — 2018
Defeats Frieza on Namek as a Super Saiyan. — 1991
The longest depicted record anybody here has, and he is fifth because several of the entries above him have scored on him directly. Ultra instinct is the real thing — a state the narration describes as moving without deciding to, and which the panels back up by having him evade things he is not looking at. The screen and the page agree about him more consistently than about anyone else in this franchise.
Destroys the Earth outright during the fight. — 1995
He destroys the planet he is standing on, on screen, with survivors escaping only because somebody teleports them out — one of the few unambiguous large-scale kills in the run, and it happens rather than being reported afterwards. Everything after him operates at a scale the story stopped trying to express in comparable terms, which is a fact about the story rather than about the feat.
One death in one work. It is the only place the record puts these two in the same room, 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.
Full receipts on the Dragon Ball ranking: Son Goku (2 citations) and Kid Buu (1 citation).