Stage-Limit According To Potential

There is a short explanation in chapter (6) on the stage limit, but I'll just mention that they are semi-hard limits. So, while they can be broken through sheer hard work, great luck, and so on, it is (generally) nearly impossible to do so for the majority of the Pokemon.

Red -> Iron (high),

Deep Red -> Bronze (low)

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Light Orange -> Bronze (high),

Orange -> Silver (low),

Deep Orange -> Silver (mid)

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Light Yellow -> Silver (high),

Yellow -> Gold (low),

Deep Yellow -> Gold (mid)

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Light Green -> Dark Gold (low),

Green -> Dark Gold (mid),

Deep Green -> Dark Gold (high)

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Light Blue -> Platinum (mid),

Blue -> Palladium (low),

Deep Blue -> Palladium (high)