This more or less has to do with the fact Chuck is the most forgettable Gym Leader of the Johto bunch and the Japanese version (apparently) didn't attempt to contact his previous voice actor, who is a big deal and an actual martial artist from what I heard. And yet, Chuck gets the honor of a small still flashback.
Sorry, I'll take a battle from distant past over Korrina's gym battle, because the former is super old and shows the writers making some kind of effort to establish continuity by referencing
actual past events whereas I don't think we need a flashback for Korrina, girl who got more than enough screentime in XY, and will return again in Pocket Monsters. Like enough already.
The lone fact they bothered to include this flashback should be celebrated. Like this fandom really surprises me. Everyone is bitching and moaning about continuity, continuity this and continuity that, and when they actually make some effort to acknowledge a battle from distant past, people....again bi
tch and moan because....why exactly? Because they don't care for Chuck? Damned if you, damned if you don't.
"Ah yes, I want all the continuity...but, no wait, not
THAT continuity WTF ARE YOU DOING, I DON'T CARE FOR THAT BIT OF CONTINUITY"
It's simply annoying.