>>38194837I think they had in mind that most attacks would be Normal. Rhydon, being one of the first Pokémon designed, only having Normal attacks adds to this theory.
This would explain why Ghost-types are treated like an "uber' type by the way some NPC talks, like being immune to Normal would be something super troublesome.
The way the NPC talks is also like Rock-type is super strong, like "it's hard to damage Rock-types!", just because it resists Normal and they usually have super high defenses. It was a type created to be super defensive.
In practice, however, Rock is the most frail type of the game. This wouldn't be true if most attacks were indeed Normal. I feel like the strong elemental aspect of Pokémon wasn't added early on the development, as suggest some early designs and the "Special" stat.
This only adds up to the many failures of the Gen I metagame. But I don't think the game is bad, though, it's still a quite complex and revolutionary for the GameBoy system.