What Pokemon are Natural Rivals?

Question

What Pokemon are rivals according to PokeDex entries? For example, I know that Zangoose and Seviper are enemies, or Heatmor and Durant. Are there any other Pokemon like that?

Comments

do we need to write why they are rivals?

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No, but if you want to, feel free.

Answer 1

Other rivalries that I can remember seeing would be between Persian/Meowth and Murkrow/Honchkrow, their dex entries stating that they've been known to steal each others treasures. Others by entry would be Kyogre and Groudon (of course), technically Cressilia and Darkrai since one creates nightmares while the other wards them off. Wurmple and Swellow are rivals since one hunts down the other as prey.
Source Bulbapedia

Comments

There are countless Pokemon that have a predator-prey relationship mentioned in descriptions, including, but not limited to, Shellder and Omastar, Cherubi and Starly, and Shelmet and Karrablast. Also, Groudon and Kyogre supposedly hate each other.

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The question is asking about rivalries, not predator-prey relationships. So Swellow / Wurmple doesn't really count.