What does it mean in this context??
Let's start with the original sentence.
Now let's simplify it a bit to mean just: Let's not mess with Piccolo Daimao again.
Now let's add back っての. っての is a variant of 〜というもの, i.e. "the one called..." or simply "that..." So we are adding the nuance of: Don't mess with the one called Piccolo Daimao again. Or just simply: Let's not mess with that Piccolo Daimao again.
Now let's add the nuance of "Well, don't know about other demons, but this one in particular we shouldn't mess with." Meaning roughly: That Piccolo Daimao? Yeah... let's not mess with them again. Or: Don't know about the other ones, but let's not mess with that Piccolo Daimao again.
For a discussion of っての, see the top answer at: What does ってのない mean?
For a really good illustration of the difference between に and には, see the top answer at: What is the difference between "に" and "には"?