Well Oli can out spam Pit's arrows with his Pikmin throw(side-B) plus the pikmin will cancel them if they collide.
Also when I'm ahead by a stock, what I'll do, (don't know if other Pit mains do >.>), is I'll just keep shooting arrows until you approach me, even if you're doing pikmin throws. They wrack up little damage, so it shouldn't be that much of a problem. I also like to jump around while shooting arrows, so i can avoid pikmin, but when a white when gets on me, I would Immediately try to get it of.(They do 6% damage each hit!)
I don't really know much of the Oli/Pit match up. All i know is that it's one of Pit's worst matchups. >.>
And yeah, that 0-death you deed on me was hilarious! Plus i hate that nair to Usmash combo! >.<