It's cause Galarian Meowth is based on Vikings and well Vikings = Dumb. Where as Alolan Meowth is based on Spoiled Cast's and they're smarter. Also it's a dark type and Dark type is "Evil" and that means "Smart and Sneaky"I mean in fairness, the anime has ALWAYS been like this. Focusing on filler episodes or formula/slice of life over actual important character development steps. Even the best series like DP wasted a lot of time.
I admit this episode being mostly a Team Rocket faceoff kinda underwhelms that key step (though I get the feeling Goh's hardly being written out) though it was at least a decent creative faceoff that charted back to some of Goh's Pokemon and their development. They should have tried more stuff like this with the Gacha.
Interesting that TR Meowth was able to sweet talk his Galarian cousins to be on their side but gets on horribly with his Alolan ones. Also TRio being unwilling to snag Ash's Pokemon before the big match.
On a side note, it's kinda goody goody, but I liked the whole 'defeat equals friendship' thing continued on, with both the Zigzagoons and Perserker's gang getting some food in the end. Hard to really see a starving stray as a bad guy.