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I think a lot of people don't realize that "Leave _____ to me" is supposed to be sarcastic/ironic. It started by mocking jobbers in anime like Krillin by saying "Leave Frieza to me" since Frieza ends up defeating Krillin with next to no effort. It comes from the trope that a supporting character tries to buy time for the main character to complete their objective by challenging the villain. They say something like "You go on ahead. Leave this guy to me". The supporting character is then defeated to showcase the villain's power.
You're not supposed to say "Leave Toxapex to me" with a picture of Starmie because Starmie is actually good at dealing with Toxapex.