Some notes on future single stage Pokémon.

First and foremost, due to increasing emphasis on single stage Pokémon, these species have seen a massive power creep. Traditionally, single stage Pokémon existed primarily as fodder for future evolutions, but since Mega Evolutions that idea has been put into bus. Recent single stagers have higher BSTs and powerful forms. In addition, many of the weaker ones have now retconned BSTs that make them more powerful. This makes them indistinguishable from second stage Pokémon(Wishiwashi is the most egregious example of this. Its school form is essentially a Level-Up evolution.)

Secondly, is how the power creep progresses. The power creep is around 20-30 BST for every even generation. This means that within three generations, single stage Pokémon will have an alternate form that will reach to Uber level, while common high end ones will reach to the level of starters and Haxorus. That's terrifying.

This gives us some weird ideas:

-Pikaclones: Looking at BSTs of Pikaclones:

-Gen III: 405, Gen IV: 405
-Gen V: 428, Gen VI: 431
-Gen VII: 435
-Gen VIII: 436

If we continue with this;

Gen VIII: 435
Gen IX: 458, Gen X: 461
Gen XI: 465, Gen XII: 465
Gen XIII: 488, Gen XIV: 491
Gen XV: 495, Gen XVI: 495

So, within six generations(18 years) we will have a Pikaclone that is just as powerful as Raichu. Neat.

Edit: Due to Morpeko changing things, the current situation looks more like this:

Gen 9: 440, Gen 10: 441
Gen 11: 445, Gen 12: 446
Gen 13: 450, Gen 14: 441
Gen 15: 455, Gen 16: 456

-Joke Pokémon: Looking at the current stats, the most powerful of them is Chatot with 411(technically Stunfisk with 471 but it has high stats due to its unique typing). However, both Pyukumuku and Corsola now reside at 410. While much improvement cannot be expected, we can see that this section is rather, dying. So we will not care for it, until it is revitalized.

-Low end species: With Qwilfish buffed to 440, this group's new borderline seems to be 440-460, as opposed to 430-460. It is likely that this group will take over the conventional weak 455 BST two stagers in the coming generations.

-Medium end species: With Lunatone and Solrock buffed to 460, it seems that borders of this group now start at 460 rather than 440. In the coming generations, this group should take over conventional second stagers.

-High end species: With Cryogonal buffed to 515, this group no longer ends at 490. While the gap still needs to be filled in, within next generations, this group will take over high end dual stage Pokémon.

-Alternate forms:
The maximum limits for generations are:

Gen IV: 520, Rotom forms.
Gen VI: 615, Mega Aerodactyl
Gen VII: 620, Wishiwashi School Form

Looking at this, within three generations it might be reasonable to expect an Uber-like form.

-Fishes: Looking at them:

Gen II: 430, Qwilfish
Gen V: 460, Basculin
Gen VII: 475, Bruxish

Looking at this, we can guess that;

Gen IX: 490
Gen XI: 505
Gen XIII: 520
Gen XV: 535

Within eight generations(24 years) we can expect a fish around Lapras' level.

-What else:

• It is unlikely that there will be single stager around the level of a legendary in the foreseeable future. There can be a Silvally situation, however.
• While single stagers have started to drive out two stagers to higher levels, they have not started to drive out three stagers yet. That will take time.
• Due to their currently limited amount, it is unlikely that single stagers will see significant boosts in the upcoming generations, though stat retcons will continue.
• Single stagers can take more archetypes. They have currently took over traditional fish archetypes, it shouldn't be unreasonable to expect them to take over other early route Pokémon, such as rodents, birds etc.

Edit (18.12.2019): Changed Pikaclone segment.