Were Rhydon and Onix only Rock-type in Gen. 1?

Question

I the Anime when Ash was battling Brock, Pikachu's Thunderbolt effected Onix. For Rhydon I was just wondering.

Answer 1

No, that was a mistake made by the people that make the anime.

Comments

So Rhydon was Rock and Ground-type?

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Yeah it was.

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I thought there weren't Dual Types in Gen 1...

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I searched before I answere and came to no such conclusion.

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There were dual types in gen 1. I own yellow.