I've read this guideline and I find it faulty. Half of our discussions here can be suppressed by it if you think about it. Way earlier, I made a point why Treecko should not be in the same tier as Shroomish since it struggles much more for a longer period of time. Sumwut, in his argument about Zubat mentioned how Oddish is similar in terms of usefulness. Hell, even you were inclined to lower Groudon's and Kyogre's tier because of Rayquaza's better performance in late game.Some guidelines to follow:
- We do not decide the tiering of one Pokémon based on its performance relative to another Pokémon. It does not matter if Pokémon X does the same thing better than Pokémon Y; if both are good enough for the same tier, they will be placed as such. (e.g. Corphish should be E-Tier, because Carvanha does its job way better)
My point is that grass types have an easy time in the later parts of the game but it doesn't mean much when most of water Pokemon found on Routes 124-134 faint in 1-2 neutral hits anyway. In my playthroughs, I am able to freely switch between my Pokemon are train them equally because this segment of the game is such a cakewalk.