I can help you.
When you are playing, watch your opponent more than you watch yourself. Imagine you are your opponent. Try to predict how your opponent would react to something, and put yourself in a position to punish that reaction. For example, grab release. If someone gets out of Olimar's grab release and then jumps away, they can't be punished. However, most people don't know this, or don't react fast enough. So when I grab release somebody, instead of trying to immediately release an attack, I'll charge a downsmash, and more often than not they will roll right into it. It works all the time, and repeatedly, against the same people.
Another grab release mindgame I love doing is I'll let them go, and then I'll immediately grab them again without moving. Almost every time after the second grab, they roll away from me, so once they've been released I immediately start running forward and then I grab again. This is excellent when I do a grab and I see I have blue or purple 2 down my line. I can rack up pummel damage and then get the pikmin grab I want.
There are all kinds of things you can do apart from grab release. Something Typh always does to me (and like an idiot I always fall for it) is when I've KOed him and he has respawned, I'll usually run to the side of the stage. he will run at me, and so my reaction is to roll to the other side of him, and as I'm rolling he has already predicted me and is charging a forward smash in that same direction. just play around with it and see what works for you.
I've been working a LOT on minimizing my predictability. What you'll end up realizing is that in order to be unpredictable, you must be able to predict your opponent.