I'm not sure about the ratio on Ness, but I have been having less of a hard time every time I play against one. He can juggle Bowser to a reasonable degree when he gets the advantage, but really...who doesn't? He gets bullied offstage pretty badly,
Mario waxes and wanes between -1 and 0.
Playing against Sheik is more difficult than Luigi, and it's only going to get worse. I've posted like 20 different times from 20 different approaches trying to explain why the Sheik MU is bad for us.
The Sheik players in your communities and Smash 4 players in general need to step it up. They have A LOT to learn and need to really become disciplined. Number one example: approaching when you no longer need to. A large amount of Smash 4 players have Brawl roots, but it's almost as if nothing was transferred between those games, and it's really bothering me. There are very few things that Bowser can do to Sheik once a sizeable life lead is established, and it's too easy to get a lead and maintain it as Sheik.
Mid level players will have a nightmare facing Luigi because he feeds off of bad decisions and poor spacing, both of which mid level Bowser players are prone to doing. Luigi's damage output from grab scenarios and punishes on Bowser are larger, but the trade off is that it's easier to get to him and hit him because his mobility is garbage, and we can bully him offstage (something that, again, players aren't doing enough of.) While all of Sheik's combos are love taps in essence, Bowser cannot catch Sheik, cannot trap Sheik, or bully Sheik offstage. Her frame data is good enough that she does not have to fear anything Bowser does. You can bring the argument of "human error" into the discussion of the MU, as someone mentioned before (and I don't doubt it, human error is rampant in this game but there are more things that attribute to that as well), but you have to take into account that a lot of players don't have enough discipline or understanding of the game where they understand that they're in a winning state. I would bet money that the Bowsers who believe the Sheik MU isn't bad do not have players that play Sheik well or understand how to hold a lead well. Sheik can just let Bowser hang himself. This is something that will continue to worsen as the Smash 4 meta develops.
The Luigi MU isn't in our favor, of course, but Sheik is much, much worse. Believe us. Bowser players, including me and everyone here, have to do a better job against Luigi players. It's a pretty intense and frustrating MU due to the state of the meta + early game, but it will become easier with time. We have the tools to make it that way.
Falcon is not -2. It will never be -2.
I'm not really going to speak on Rosalina, but there are more moves besides DA that we can use to get rid of Luma. Would you really call DA reliable before anything else Bowser has?
Villager is one of the easier "zoner/projectile" MUs bowser has to deal with in this game. People write Bowser off as one who automatically struggles the moment a projectile or two are involved in a MU. I suggest you all to look deeper. How much damage does he (Villager) do while trying to keep us out? Can he keep us out well? Can we destroy or eliminate those projectiles without taking damage? How's his grab? Is walking really good in this MU? How much damage do we do once we get in? Those are a few of the questions you need to ask yourself when looking at those types of match ups you believe we struggle with.
Walking is a super important option in this game, and it's something you have to do in that MU (if not that, then crawling) to close space against Villager.
As I said before, bowling ball isn't a problem. If you time Bowser's Up-B, a bowling ball will just collide with Bowser's shell and he won't get hit.
And also, because someone will probably mention that it's not feasible to run the clock in this game: refer my point about players lacking discipline. Playing the game for money opens up new avenues and perspectives on playstyles. Sheik will get the damage she can get for free due to Bowser's weaknesses, and then just sit back and let Bowser lose to himself.
Fun fact: all of Sheik's main tools in neutral come out before our singular fastest move.