episode 332 "Maxxed Out!" is the first time Max pulled Brock's ear,in episode 317 "The Princess and the Togepi" Max and May meet Misty for the first time and while she's visiting Misty pulls Brock's ear when he meets the princess so Max picks up the habit.
episode 472 "Gymbaliar!" Jessie of team rocket was Croagunk's original trainer but Croagunk was so creepy Jessie left it behind in the escape. Brock felt bad for it and captured it, after that he went to say good bye to a girl they encountered during the episode when Croagunk pops out of the pokeball and poison jabs him.
i will edit the answer when I find the correct episode for misty, sorry.