Like I said on that other thread, Wolf's smashes are really unsafe on shield. Just don't mash shield grab and instead think about Marth's other OoS options like Dolphin Slash, Dancing Blade and Fair (angle it forward to increase its horizontal range, it really does work and the range of Up b when angled forward is pretty damn crazy if you ask me). Try out Wolf in training mode and check his cooldown of his smashes. If you do what I said and still have trouble punishing his smashes, then you just aren't reacting fast enough. But don't worry, becoming fast at punishing just comes with practice.
Against characters with longer Marth like DK, ROB and Wolf, you have to play more like a bait-and punish game. Marth can do this well however. Marth's disjoints are very useful against those kinds of characters, because you still have the advantage of having disjoints while they don't have that. You retreat your aerials more than usual and when they throw a Bair/Ftilt/whatever their extended hitbox makes them get hit. Or position with your approaches to walk/dash and PS JUST at the range where that laggy Ftilt/Wolf Smashes hits at max range and then run and DB OoS. Because those moves aren't truelly safe even at max range if you react fast enough. And those characters outranging Marth usually only truelly counts on the ground. Once you get them either above you or offstage it's pretty damn easy to hit those characters in their blindspots ALMOST for free. Usually Wolf doesn't have that big of a problem getting out of the air, but against Marth it's different for him. If you space your Uairs well when you're below him, I think you can hit through his Shine without that hitting you, making neither take damage but you still keeping him in a disadvantageous position and probably getting a free hit with the 2nd move you throw out. Don't let characters with a strong neutral game frustrate you, you can change the momentum of the game dramatically by just landing a decent hit, which is easy enough with Marth if he's playing correctly. Wolf may not have to take as high risks in the neutral game as Marth has to (though the risks Marth has to take are also low) but he can't punish as hard as Marth can. Wolf has strings too but they usually don't lead to as much damage as Marth's strings do and Wolf's KO moves aren't as good as our's. Marth also edge guards Wolf a lot harder than viceversa (don't think like you can edge guard for free though, it's better than you'd think it is). Still overall I'd call Wolf relatively easy to edge guard, at least from my experience.
If you jump and you predict him trying to stop you with aerials, retreat more and Fair him. He extends his hurtbox when he Bairs or Fairs. Both may have more range than our Fair, but even if he doesn't throw out that aerial, our retreated Fair is usually still safe even on whiff. His own Bair is safe on block when spaced well, but even that move is punishable. Just like characters can reposition to punish Marth's Fair, you can use that tactic against Wolf's Bair too. Crouching and then shielding just before Wolf does a landing Bair will give you more frames to PS (the thing is that if you crouch and the hitbox whiffs at the height you would get hit if you didn't crouch, and then you cancel the crouch with shield, you'll automatically PS if the hitbox of that move is still active). And when you PS it's a lot easier to shield grab or DS OoS punish Wolf's Bair. Wolf can't throw out his Bairs in the same way we can with our Fair because his Bair doesn't hit like an arc, forcing him to choose more predictable patterns than we are when we use our Fair while falling down (it's still a really good move though, arguably Wolf's best one). Wolf also has a terrible fast fall while we have a pretty good one which limits his options above you and the patterns he can take when throwing out the Bair.
Marth is pretty bad above an opponent. Wolf is no exception when it comes to giving trouble when Marth is above him. But I don't want to repeat about how you get back down from opponents. Check out
http://smashboards.com/threads/ask-...-the-marth-faqs.188570/page-262#post-16324845
Still, it shouldn't be THAT big of a problem, characters like another Marth, MK or ZSS are a lot scarier than Wolf when Marth is trying to land.