That was at the start of the story story. Since then, Shanks has not had a single negative feat. Every other Shanks appearance since then has been more impressive then the last, getting better and better everytime.
And I don't think it's smart to pick on Shanks worst feat while you're defending Big Mom. Shanks only has 1 negative feat. Big Mom has at least 50 negative feats. It won't end well for you bro. Your best shot is just focusing on Big Mom's positive feats and trying to explain why they are better than Shanks positive feats.
Not a good comparison. The Marines never got in Whitebeard's way. They were just chasing after Whitebeard.
They never pretended Whitebeard from going anywhere that he desired. That's a very clear distinction compared to what happened with Shanks and Kaido. Kaido wanted to go attack a sick and diseased Whitebeard. Shanks said no you don't have my permission. Kaido backed down. That's why that comparison doesn't make any sense. The marines never prevented Whitebeard from doing what he wanted, there Whitebeard didn't see any point in harming them. Shanks prevented Kaido from doing what he wanted.
Only someone that Kaido cannot defeat can prevent him from doing what he wants. That's why Kaido was insisting on killing Big Mom if she came to Wano, and the second he realized that he can't defeat her, he then agreed to be in an alliance with her.
The marines stated that Shanks and Kaido had a skirmish. Let's look at the dictionary definition of a skirmish, shall we?
So Kaido wanted to attack Whitebeard. Shanks said no. Kaido and Shanks had a fight. Then Kaido ran away. Those are the facts. You remember how Kaido was introduced as having a certain amount of loses in his introduction? It's a manga fact that Shanks was responsible for one of them.
Shanks didn't talk to Kaido, he fought him and won. And I don't like the condescending way you said "because he's actively going to the Holyland and talking things out with the most corrupt people on the planet". Shanks' meeting with the Gorosei highlights just how important and powerful he is. The Gorosei literally said they would stop their busy Reverie schedule in order to have a meeting with Shanks. This is similar to the respect Sengoku displayed Shanks when he agreed with Shanks demands to end the Marineford war and to leave Whitebeard and Ace's corpses with him. The respect the marines and Gorosei have shown to Shanks is out of this world.
Shanks is by far the Yonko with the best feats, best hype, and best portrayal. And he's the pirate closest to One Piece.