In POKÉMON: DIAMOND AND PEARL, why didn't let ASH or DAWN pull BROCK's ear?

I goes since its more creative for Croagunk to Poison Jab Brock. IDK, but I really think that since ash never pulled his ear before, it wouldn't make sense. And since Misty pulled Brock's ear in the first season, having Dawn do the same would be like a repeat.

At least that's what I think.