Gary Oak is the best-supported answer. In a September 13, 2023 retrospective, The Pokémon Company International ranked “Gary Oak and Ash” first among ten animated rivalries. Paul is the strongest alternative if you define “biggest” as the rival who fought Ash most sharply over how Pokémon should be treated and trained.
What “biggest” means in this question
The word is a judgment, not a measurement. No official statistic tracks screen time, battles fought, or win rates across Ash’s rivals, and no published figure measures how large any rivalry was. The strongest evidence is an editorial ranking: the 2023 retrospective, Pokémon Animation’s Ten Greatest Rivalries, places Gary first and Paul tenth. That ordering reflects the publisher’s view, which is useful as an authoritative reference point but is not a scientific finding.
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Why Gary Oak is the standard answer
Gary is the rival most often named when fans and official material describe Ash’s journey as a whole. Three points support that position.
- He is there from the beginning. Gary is Ash’s childhood friend, and the retrospective frames their contrasting starts as the foundation of the rivalry.
- The rivalry pays off on screen. Official episode summaries for the Johto League Silver Conference describe Gary as Ash’s “long time rival,” set up their battle, and state that Ash was “thrilled to have finally defeated his rival” afterward.
- It ends with a reunion. The retrospective returns to Gary and Ash’s reunion in the closing episode of To Be a Pokémon Master, which is why it reads as the rivalry’s long view rather than a single clash.
A licensed Scholastic storybook, Young Ash, Go West! by Tracey West, also refers to Gary as “Ash’s biggest rival” in its preview. That line corroborates the conventional label, but it is fiction written for children, not an independent ranking.
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The case for Paul
Paul is the rival who makes the strongest argument against Gary. His conflict with Ash is ideological rather than personal. The retrospective contrasts Paul’s harsh approach to Pokémon with Ash’s kindness, so each encounter tests how a Trainer should treat the creatures they battle with. Ash’s eventual victory over Paul in the Sinnoh League closes a sustained dramatic arc, which is the sort of tension that makes a rivalry feel “biggest” to viewers who weigh conflict above history.
The same 2023 list ranks Paul tenth, so the official editorial view puts him behind Gary. Paul’s case rests on intensity and theme, not on the rivalry’s length or its place in the series’ framing.
Quick Recap
Rank #2
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Gary and Paul compared
| Criterion | Gary Oak | Paul |
|---|---|---|
| Rank in the September 13, 2023 editorial retrospective | 1st of 10 | 10th of 10 |
| Relationship arc | Begins with Ash’s journey, becomes less hostile over time, and ends with a reunion in the closing episode of To Be a Pokémon Master | Introduced as a harsh rival whose treatment of Pokémon directly clashes with Ash’s values |
| Ash’s competitive payoff | Ash finally defeats Gary at the Johto League Silver Conference | Ash defeats Paul in the Sinnoh League after a sustained rivalry |
| What the character represents for Ash | The formative measuring stick and long view of Ash’s development | A test of Ash’s training philosophy and his bond with his Pokémon |
| Basis for the comparison | Official retrospective and official episode summaries | Official retrospective; the contrast in treatment of Pokémon is the retrospective’s own interpretation |
Choosing the right answer for your question
Your criterion decides the answer.
- If you mean the rival who shaped Ash’s journey from start to finish, and who is most closely tied to the series’ framing, choose Gary Oak.
- If you mean the rival who most directly challenged how Ash trains and treats his Pokémon, choose Paul.
- If you are asking which rivalry an editorial ranking rates higher, the answer is Gary Oak.
Limits of the evidence
- The ranking comes from a single retrospective published on September 13, 2023. It is not a survey of viewers, and no named individual has been quoted saying which rival was biggest.
- The episode and book references describe historical content. Streaming and retail availability change over time, so check current listings before watching or buying.
- This answer covers the animated series and its licensed material. It does not measure how the Pokémon video games characterize Gary or Paul.
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