As someone with the highest volume of -4s in the game, I wanna emphasize the severity of a -4 and exactly what it implies. -4, to me, is when the only option you have involves extreme risk, and makes you available to be killed with extreme ease, e.g. Falco/MK/Oli/ICs for Ganon. At no point can Ganon select a safe option or intelligently defend against them, because they have too many options, and he has too little to discourage or preclude any of theirs.
When I envision Falcon vs. Pika, or Mario vs. MK, I see them having an extremely difficult time, but not being so profoundly overwhelmed that their only recourse is to commit to virtual suicide with each move.