I was intrigued when I first opened this thread, & after scanning, I thought this is definitely not something for beginners. I mean, in most games, you will often be very under-levelled come the E4, & when you factor potential evolutions, it is pretty easy to find yourself frustrated with having to grind far more often than a Nuzlocke.
That said, there is a pretty easy loophole trainers can easily exploit, particularly in the earlier games: Every time a Pokémon levels up, & it is about to evolve, make said Pokémon faint before the battle is done. Apparently, Pokémon do not evolve when fainted, assuming level by evolution, which pretty much allows you to use certain key Pokémon for far longer than expected. Of course, this only works with trainer battles, but if you play it right, you can keep your key Pokémon in your party long enough to take on key match-ups, boosting your chances of getting through the game faster.
Nonetheless, I am intrigued at how this thread will unfold.