The only thing I'd suggest that hasn't been mentioned in that Reddit thread would be, try to work Quick Draw into your arsenal. It's absolute pants for damage, and overuse is sure to get you punished, but for someone with mobility as limited as Ike's, having a burst of speed he can pull out both on the ground and in the air is still pretty valuable. A few times in that match you were sort of just idly floating back to the ground in pretty precarious positions, Roy definitely could have pressed his advantage harder when you were trying to land, but QD can let you mix up your movement without staling your dodges. You can feint going one way before zipping the other in order to escape pressure, you can chase landings that are too risky or unpredictable to use dash attack on, and perhaps most importantly, you can increase the amount of space you can threaten to make opponents think twice about approaching, giving you the breathing room to keep your spacing up since Ike really does not like when a foe manages to get in his face.
Sorry for the poor quality!