Pit's approach options are actually a bit sketchy imo. SH Fair is pretty good vs taller characters and SH Aerial approaches in general. SH Nair is pretty decent for stopping some grounded approaches, but it's smaller range makes it so that it's easily stuffed but longer ranged moves (the animation is a lot bigger than the hitbox).
Pit's mostly a defensive character. He baits approaches and tries to place the opponent in awkward positions where you can punish them to the fullest, mostly with Grabs. He's particularly good at catching landings via a variety of different ways (Dash/Pivot Grabs, Dash Attacks, Aerials, Arrows, SideB).
But that's his punish game and a different topic. You wanted to know how to deal with Defensive play. That's actually one of the hardest players to play; the Reactive Player. They let you make the first move, and Pit doesn't really have a bunch of moves that are safe on shield. The closest is maybe Landing Bair at max range. For these people, I like to try to figure out their main go-to defensive options, be it rolling, spotdodging, or holding shield. From that point on, I try to continuously punish that option to force them to either switch options, or play more aggressively.
Ex. The enemy Luigi knows we want to grab them. He'll sit still and when you run up to his face, he'll spotdodge. We can cover spotdodge in a variety of ways. SH Nair will last longer than the Spotdodge's invincibility, Pivot Grab will get him right as spotdodge ends if timed correctly, or you can just read the spotdodge, run up to him and SideB/Pivot FSmash/whatever. He eventually gets sick of taking damage, switches to rolls. Same story there. Cover his options and force him to mix it up.
Basically do whatever you can to put them out of their element, or make them play more aggressively. Once they play more aggressively, then we can go back to our original gameplay of baiting out moves and punishing them.
Every option they do can be beaten with something. A correctly spaced SideB will stuff their faster attacks if you space correctly and get the super-armor. Depending on how strong the move is, you can space FSmash to get only the second hit and completely outrange almost every Jab/Tilt in the game, and beat it out. This will eventually force them to shield more often, which is what we want, meaning that we can Grab them more. See how that all works out?
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I've written up this Pit Guide detailing a lot of different things about Pit. Check it out when you get the chance!
https://docs.google.com/document/d/1Va9GvzFaCZnF4xtyGPScFFJ9gEGaTO-xZDELbBJLe7Y/edit#
