Unless I am wrong here (and god knows I've been wrong way too many times in this battle), STAB doesn't negate being sluggish, so Giga Impact was supposed to fail.
Regardless of that (although I still want to know the ruling) I've made a ton of little yet very debilitating mistakes throughout the challenge that made the victory kinda unlikely. I'll need time to reform my strategy and try again later.
Also, I've just noted that I have 4 battles going on (assuming subway and hall count toward the total). So yeah. I think I have to get rid of one.
"You know? you are not half bad. Neither of us deserve a stalling match, so I'll give you the win this time. Next challenge I will mop the floor with your smugness, but meanwhile, congrats. Also I still think you need a restaurant wagon".