>>54690083To expound upon this
The functional difference of a level 40 fighting a level 60 is comparable to that of a level 26 fighting a level 40. While the latter scenario is not particularly ideal to be in, you can see that it's not an extreme situation. Add to the matter that your level 40 typically has EVs racked up and usually some amount of IVs greater than that if an NPC pokemon, and your level 40 effectively operates as more of a level 45-50. Carrying this knowledge back to our scaling example, that means that your level 40 facing a level 60 is now in fact more comparable to a level 33 facing a level 40. The higher level pokemon clearly has an advantage still, but the advantage is easily mitigated by a movepool you've sculpted throughout your playthrough, as well your knowledge and abuse of type matchups.
To put it succinctly, the level curve actually doesn't matter for shit. What you think of as objectively stronger stats aren't really that comparatively strong. There's a reason you can complain about the disparity AND gloat about overcoming it in the same breath.
Johto's primary offense isn't the bad curve - it's that that curve is too low to fully evolve a number of pokemon, and the extra XP late game is so dried up that you have to funnel EVERY battle into a new member if you're adding someone to your roster late.