>>32196176The tiers are only based on usage. So generally if there is something similar but even slightly stronger, it will see more usage. Or sometimes things end up in high tiers due to perceived value or general popularity. People thought Electivire was strong enough for OU in the beginning of Gen 4.
But being somewhat outclassed by another Pokemon or not seeing enough usage due to things like megas, legendaries, UBs, etc. does not make a Pokemon objectively bad.
Espeon can be used with relative success in standard. It just isn't "click to win" like a lot of Pokemon are now.
