The anime is not something you would take seriously lol, 99% of what happens is gone in the next arc and will never matter again. (That 1% being Pikachu and the minor)
Unova:
Ash 'sends' his pokemon to Oak, 90% of them are now erased from the universe.
Ash is 10 and starts his journey with Pikachu.
Pikachu somehow loses all his powers because of stupid-ass reasons. Usually Pikachu just turns into a piece of turd every new region but at least they had a reason why now.
Ash and Pikachu are probably the most experienced trainers on the face of the earth, but he loses to someone who never touch a Pokemon before because apparently the anime wants to make the long time watchers rip their things off.
In the interest of time..
Ash forgets how to catch a Pokemon and runs after a freaking Snivy like a vietcong.
In the future after showing you sh**tons of fillers and when unova is old news and Ruby Sap Remakes are out..
Ash gets 8 badges, beats Team Plasma's ass.
Joins the regional league, beats rival.. Rival turns friendly towards Ash.. Ash loses in semi-final.
Repeat
So? Hasn't Family Guy been on for like 10 years and every few episodes or so they mention "years later" like when Stewie kills Lois how they mention that 2 years pass. Yet Stewie is always a baby, Meg is still a teen girl, Chris is always a teenager, Brian should be like near-dead by now, etc.
'Stewie kill Lois' never happened, Stewie was simulating what would happen if he went to kill her.
Never-age is reasonable in Family Guy, it's a random comedy after all. When Pokemon get constant flashbacks and jokes about everything then maybe it would be a reason they should deserve immortality. Because right now, the creators of the anime are too scared to make something fresh.. They are scared of losing their audience and popularity if Ash and Pikachu are gone, and if they want to keep em they have make Ash start out 10 again, clueless about Pokemon, Pikachu weaker, and so much more.