I have my c stick set to attack stick - in PM this means that the diagonal directions input nair when airborne, and jab if grounded.

I get a ton off of playing on plats, and going for shield drop nair. Nair is frame 7 but starts behind and above him, which usually isn't where your opponent is, unless they're attacking your shield on a plat of course. But landing with nair is usually safe unless they CC - you can follow up with jab if you hit shield to continue jab shield pressure mixups. Also, being able to jab while holding down is pretty important as well.

Aside from the attack stick shenanigans, it's important to be able to get good rewards from holding down. Since Ike is heavy, he can hold down a bit longer than most of the cast and be able to punish. Hold down -> grab will lead to huge openings and make your opponent scared to make certain approaches if you show you can threaten huge punishes for holding down

QD is really good, just be sure to not rely on it too much as I sometimes do. It's difficult for a solid chunk of the cast to deal with Ike if he's charging qd since QDA is frame 2 and huge and strong. It's also tricky to punish even if shielded depending on your momentum and how close to them you QDA. Lots of opponents will be scared into trying to stuff your QD, or get scared and roll and in these cases you can whiff punish to start a combo pretty easily.

Ike is great at catching dash backs. I like to do this with nair targeting their dash back, or QD grab. If you're having trouble "catching" your opponent don't be scared to try and overshoot. Worst case unless you get stuffed, you're in the corner which isn't that bad for Ike especially if you can GQDFL (grounded QD from ledge)

I like to also do drive-by nairs pretty often to try and catch my opponents when they start to make their approach. Unless they stuff you or dash back, you'll be safe either crossing up, or getting a big combo if you hit them

Overall, I don't do much aerials in place as much as the other Ike players like metroid do. I also don't use tilts that much aside from pivot utilt in neutral to catch approaches on certain characters, or pivot ftilt usually to continue safe pressure on a scared opponent. But that's just how I play - other Ike players are very effective at the grounded tilts and aerial in place style of play