I will do two separate posts on them.
Pit:
What moves or tactics should we watch out for?
-Arrows are probably the number one thing that will first come to mind. When the match starts, be prepared for an arrow to the face. Arrows are just good at annoying, good for camping, decent for edgeguarding, and just overall versatile and fast. Note that it can clank/cancel with a lot of Lucario's moves, but arrows are one of the faster projectiles in the game and can be charged. Sadly, some Pits rely on arrows too much for their own good...just go look at the number of ATs for arrows!
-Angel Ring and Mirror Shield: two reflectors! Needless to say, do NOT spam Aura Sphere haphazardly in this match. Getting a AS reflected to the face is not fun and can kill you. BE CONSERVATIVE WITH AS. Alternatively, you can still hit Pit while he is using these moves, but you must learn how:
--For Mirror Shield, you can hit Pit's head and legs, but you have to be super accurate. You can try to time Aura Sphere so that he LANDS on it while using Mirror Shield. Remember, it only protects his immediate front, so his body is still a hurtbox. Also, a grounded one has Super Armor right when Pit takes the shield out, but this rarely happens.
--Same rules essentially apply to Angel Ring, it only protects his immediate front. His body is still a hurtbox. You can hit his head or feet, but you have to be super precise. Also, Angel Ring has slightly more startup lag, I think.
Overall, if they try to reflect a projectile and miss, you can punish them during their cooldown lag.
-Mirror Shield can reflect and turn you around when you connect with any non-projectile move, including fsmash's Aura. I'm not sure if it affects Lucario's recovery. Regardless, be aware of this property.
-Fsmash is one of his main kill moves, and they love to spam it for damage. You can SDI the first hit and avoid the second, but you must have good reaction. Comes out super fast and doesn't have much ending lag.
-Bair is another kill move to watch out. Initial frames are the strong hit, but the later frames are weaker. Think of it as a sexkick.
-His Dtilt can spike, but it's very rare that a Pit will land it. Just know that it can.
-His Utilt comes out super fast.
-He has a glide, so watch out for his glide attack.
-Nair and Uair are multihitting moves and last for a pretty long time. Lucario's dair can challenge his uair, but don't be surprised if he hits you. I'm not sure about Pit's nair vs Lucario's fair. Also, Pit's uair can reach through thin floors near the edge, like PS1, so watch out for this tactic. But if you see a Pit try this, use dair. The result will be a stage spike.
What moves or tactics should we try to enforce in this match up?
-Learn to control Aura Spheres. In terms of ground game, Lucario probably wins in this department as long as you keep yourself well spaced. Aerial game, both have pretty good.
-If you're trying to recover, expect LOTS of arrows to be shot at you. Fair can clank/cancel arrows.
-If a Pit is recovering with his UpB, try to hit him out of it. If he doesn't cancel it, it will mean automatic death. But if the Pit is recovering low, expect them to fly under the stage to the other edge, or be risky and try to mindgame you and then go back to the original edge.
-Don't let arrows pressure you. Getting frustrated will not help you.
Do you feel Lucario has an advantage in any particular scenario of this matchup?
-I believe it is evenish overall, slightly in Lucario's favor. If you want numbers 55:45 or 60:40 at most.
Do you feel the opponent can shut down aspects of Lucario's game?
-Just don't be spam happy with Aura Sphere. Otherwise, not particularly.
Counterpicks? What to avoid and what to enforce?
-The usual Yoshi's to start off, if not then, then anything else would be fine. I would avoid FD if possible. I don't think there are any particularly strong Pit neutrals other than FD.
-Counterpicks...I find Frigate to be okay, but Luigi's is good choice too, I guess. Large stages without any platforms allow unhindered arrows and hit and run tactics. Try to avoid them if you hate arrows. Some Pit players love Norfair because it is big, has lots of edges, and can promote hit and run tactics. Some might try to take you to Rainbow Cruise. PS2 has the ice part which allows Pit to cross along the entire stage with one Angel Ring.
I'll probably change some stuff if I can think of anything else to say. Expect TL sometime today or tomorrow.