Marshadow is a powerful Pokemon. He’s definitely not someone that you can afford to underestimate. Trust me, it just won’t go well. Still, Bass is the strongest being in all of media so you can cut him a bit of slack there. Even if he looks down on Marshadow to an extent he will still be able to pull out the win. You just can’t hope to stop a being of his caliber. One Darkness Overload attack and it’s all over. Bass wins.