If it's Lucario you're ****ed.
This.
I know this situation quite well. I play against a rollspamming Lucario often, and it honestly is harder than it sounds to punish effectively. The frame data supports this.
I can get a few punishes in, but eventually, I fall into the trap of getting grabbed and thrown while the Lucario retreats to the other side of the stage. His short-hopped Fair>Dair can also catch me off guard. It is really annoying knowing how easy this SHOULD be to punish.
In my case, the Lucario rolls all the way to one side and stands on the ledge, aura-spamming, and every camping strategy except Snake's (or diddy's nanners) becomes useless. He WILL NOT approach, no matter what, and this get's annoying. I can easily predict his forward-roll that occurs 90% of the time I approach, but it is very hard to hit him before the second roll, as he makes his way to the other side of the stage.
The only movement style he uses is rolling. I used to have the problem of only rolling or running, and have since learned to walk (especially with Marth). It's a pitty though, knowing that if I mained Lucario, I wouldnt have to. It really comes down to character-advantage here. Lucario's roll is stupid, and impossible to guarantee a punish, unless you're metaknight and whorenado.
I am still trying to find a way to deal with this, but for the most part, it works to just predict and punish. When you miss, it's because he rolled twice consecutively, and unless you do something dumb, he can no longer counterstrike. With Marth, try approaching with a short hopped just-past-tip-range Fair, followed by a retreating Fair (back on control stick, forward on c-stick for best results). This will keep you always in either a neutral or advantageous position; but it relies on the Lucario's approach as he reacts to your "approach." Mix it up.
Try these mix-ups with Marth:
shorthopped Fair>retreating Fair
SH Fair> dancing blade (one hit, unless you make contact) This can be done backward if he rolls behind you, or forward if he stays put.
SH Dancing blade (sideB as soon as you leave the ground) > Fair/Bair/Uair as you land. Uair will be the best for you, for it's autocancelling, but it is limited in it's hitbox. The sideB's momentum cancellation helps mind-game, but only when it's mixed up with other approaches.
My favorite is SH fair, or dancing blade > shield breaker. But only do this if you notice him staying put and shielding often. You can be smart and have it tip perfectly, and follow up with a Fsmash the other way as he will most-likely start roll-spamming towards the other ledge to regain his shield. It's not guaranteed that you'll even make contact with the Fsmash, but if you do, and he doesnt power-shield, this WILL BREAK HIS SHIELD if it doesnt just hit him anyway. It's a long shot, but it's relatively non-punishable, since he will be in retreat mode, not counterstrike mode. DON'T BE PREDICTABLE WITH THIS. Try it only once or twice in a match, and only follow through with the whole thing if it's going your way.
Also try full-hopped Fairs once in a while, especially if he tries going to the air. Marth's Fair vs Lucario's Fair is kinda stupid and can go either way sometimes, but I think Marth technically has the advantage. Just don't find yourself in the air against a standing Lucario. Space smart, and you'll do fine.
But long story short. If you main MK, JUST WHORENADO AND YOU WILL BE FINE, NO MATTER WHAT CHARACTER. A rollspammer will lose to whorenado every time.