>>37215741Dugtrio with arena trap
Magneton with magnet pull
Azumarill with huge power
Then there's all the pokemon that became more viable after the physical/special split stopped fucking over their moveset
Then there's all the other pokemon that got boosts due to new abilities in Gen 5 (especially politoed and ninetales)
There have been tons of times where pokemon have been improved without needing any of that extra bullshit.
And it's also not like state readjustments can't happen. Duggy and Nidoking got base stat tweaks in Gen 6 IIRC, for example.