When the Anime started, it would annoy me to no end. But now that he's said it so many times, we know he really never will see them again, so I've just accepted that he says it. Not like we can change it or anything...
it is not true , ash didnt say that to everybody , he said to some trainers and battled them again (i know that not all of them) for example the dittos trainer and zigzagoon trainer , dont think before typing something?
No because he says it to everyone now. And honestly I never want to see any filler character from AG ever again. Except maybe that fisherman looking for Whiscash, he was cool.
that is ash's catch phrases. sometimes he does meet them again but rarely. i hate the wannabe people since they convinced theselves they are going to meet up with ash again.
Most of the trainers he says that to, he never meets up with them again such as people who are not important characters in the story. It gets quite corny after a while:
Ash: "I hope we'll have a rematch someday."
Trainer: "I'll look foward to that."
The thing is, revisiting some of those old Kanto characters would've been a much better way to utilize the Battle Frontier filler episodes than creating all-new characters for them.