>>53279611My headcanon is the MCs/male MCs that don't show up in the anime start their adventure a year later and actually finish the bad guys/catch the legendary.
So Jimmy who's shown in the anime finishes the team rocket remnants in Jhoto while befriending Silver and they catch Ho-Oh and Lugia respectively.
Maybe he becomes the next in line fire type gym leader for Indigo (Blaine has to retire due to ties to dubious research by team rockeg).
Brendan gets dragged around by May on his first year but because he has studied up (I mean his dad is literally a genius Pokémon professor in this continuity) he blazes through the gyms while breaking down Team Magma/Aqua groups, sticking it into Courtney and eventually catching the legendaries/finishing the delta episode plot.
Probably doesn't become champion (declines the title) but some sort of international supercop.
Lucas travels with his cousin Dawn after finishing a volunteer internship as assistant for Rowan.
Both challenge the gyms and blaze through them (much to the annoyance of Barry who doesn't get that they are related).
He ends up jailing Cyrus and sticking it into the crazy redhead of his gen.
Hilda and Hilbert with their partners Rosa and What'shisname rip apart N and his lot before being entrusted as guardians of Reshiram/Zekrom.
Calem spends most of his journey trying to dodge thots, capturing team Flare remnants and only trying to become a famous actor while seeing the league challenge as his way to become famous.
He ends up taking the league seriously and falls dick first into Shauna.
Ash is technically the canon protag for Sun/Moon and Galar I guess so we don't see those ever.