This doesn't directly answer your question about brick walls, but it will give you some new things to think about based off the (very limited) information I have from you.
Ganondorf more than many other characters is about SPACING. Sure, every character has to space correctly in order to avoid getting poked, sniped, grabbed, etc, but not every character has as much lag as Ganon. You should be constantly watching the position of your opponent and as soon as he's within dtilt range, things get better quickly. Dtilt is my current go to move. I used to use jab a lot in similar instances, but now I reserve jab for more OoS and necessarily quick retailations/punishments. You should familiarize yourself with the general pop up range of Dtilt on a medium weight character at various percentages. Then adjust these expectations accordingly if you're playing Jiggs or Snake.
Also important is buffering and reverse buffering. Unbelievably important. For some reason, everyone loves walking into Dair->buffered Fsmash at least a couple times a match. Often the dair is used on retreat to get spacing correct for the sweet follow up Fsmash. You should learn to buffer jab, dtilt, ftilt, usmash, and iDA (did I miss anything?) out of Dair/thunderstorm, uair, jab, tilt, usmash, FJ/DJ Nair landing. You need to be able to buffer and reverse buffer reliably in order to advanced your "wall" on both advance and retreat as well as in order to just keep up with most other characters in general. Many of these buffered moves come out a lot faster than you might expect.
Learn all your Gerudo guarenteed follow-ups as well as the spacing necessary to land a dair out of a roll-up animation. Learn to predict the rolling/get up patterns of your opponent quickly, because you'll probably be paying a lot more attention to their patterns than they will, meaning you're at the mind game advantage.
Again, all of this must be applied in a game which is first and foremost about SPACING. It comes back to that. A lot of these moves, when missed, are punished brutally. I realize now that this post has very little to do with your OP and is really just more of a Ganon crash course, but take from it what you will. Probably everything I said here is more eloquently assembled in one of the ganon guides (check out swoops' guide. It's the most up to date by a long shot), but at least I've hit the main points:
Spacing
Knowing how to buffer/reverse buffer
Spacing
Knowing all your options out of gerudo and making informed predictions about their get up based off of patterns/habits.
Spacing
FSmash, USmash, and FJ Nair are pretty good for mindgames 
