I don't really have any tournament experience, but some stuff that you should (and probably do) know, though:
1. Aerial Klaw's range is much bigger than the grounded one, and it allows for an easy ISJR, which aids mobility. You can also do all aerials except for DAir out of one, and then continue Klaw Hopping.
2. Aerial Klaw negates most of Bowser's ending lag, including that of Aerial Up-Bs.
3. He can grounded grab release every character except DK, and can Aerial Grab release some characters. Some aerials are guaranteed after an Air Release, like an UAir on Jigglypuff.
4. His FTilt has amazing range, his Utilt is powerful and mostly hits behind him, and DTilt is a good kill move.
5. There's a damaging shockwave from his landing after using USmash.
6. His only SH Autocancelling aerial is FAir.
I'm not a very good Bowser, but I know the basics and like using him.
I wish you luck! Hope that wasn't all stuff you knew.