Meowth's big speech at the end, which doubles as a Moment Of Awesome for him.
Meowth: It's only natural to wonder about who and where you came from and someday these little ones are gonna want some answers. Only there won't be any, not if you make everybody forget! So what if their parents were clones? They're all living creatures. They deserve to live, and they deserve to know about themselves as much as you, or me, or anybody does! That's what we think.
Meowth Clone: (meows in agreement)
Ash: I think we should remember too. Meowth is right.
Brock: And just forgetting things doesn't change the fact that they happened.
Misty: Don't you think everybody deserves to know who they are, and where they came from?
Mewtwo: ...Yes, they deserve to remember.