Movie Characters Appearing In TV Episodes

[PokéSean]

Sorrel and Verity should've appeared instead of Brock and Misty, especially because of the flashbacks featuring the events of Bye, Bye, Butterfree. This did air after the movie remake of the television. Once again, we didn't have characters like the Genesect too appear in the TV show.

Will flashbacks in the anime show Damon being Charizard's OT instead of Cross?

 

[Black&White]

But the events of movie 20 were in an alternate universe. Ash never traveled with Sorrel and Verity in the main anime series

 

[Daenerys]

Will flashbacks in the anime show Damon being Charizard's OT instead of Cross?

You mean Damian. And why would he be retconned out of continuity in favor of Cross in the future? Ash never even met Cross in the main anime's timeline.

 

[Gengarzilla]

Sorrel and Verity should've appeared instead of Brock and Misty, especially because of the flashbacks featuring the events of Bye, Bye, Butterfree. This did air after the movie remake of the television. Once again, we didn't have characters like the Genesect too appear in the TV show.

Will flashbacks in the anime show Damon being Charizard's OT instead of Cross?

Absolutely, positively, definitely no!

As others have already mentioned, M20's events take place in an alternate continuity. Ash of the main anime has never met any new characters from this movie and it's actually possible that they don't even exist in this timeline at all. Suddenly overwriting Brock, Misty, and Damian with no explanation would be ludicrous.