EDIT: This is regarding the Bowser vid, so you know.
Eh, it was mostly spacing issues that you'll learn with time and practise. Though this: "f-smash definitely won't touch him." while mostly true, isn't exactly true. It CAN hit someone holding onto the ledge and CAN be a decent edge guard, but the spacing has to be VERY precise. I've never done it successfully myself, but I have seen it done so I know it's possible. Mostly, it's best not try as their are usually better options.
The Bowser Bomb really has one purpose and that is to get back to the stage as Bowser will auto grab ledges. So if you find youself in the air, something Bowser can deal with, but would prefer not to, just DI to the nearest ledge and Bomb to it. From there, you have much better options. It's great if someone thinks they can hit Bowser from below and you have a ledge beneath you, because DownB his priority over... well, almost everything. And it's start up lag is very minimal. DownBing to the center of the stage is not a good idea. Too much lag. Most of your Fsmashes were pretty well spaced, but it's not something you should relie on. Ftilt, Jab, Grabs, SideB, and UpB should be the moves you use most often. Ftilt and Jab because they're his faster moves with darn good range; Grabs because Bowser has a large assortment of options with grabs (see appropriate thread); SideB (see also, Special Grab/Koopa Klaw) because it does good damage, pretty good KO potential and sets up Bowser's better aerials nicely (Uair, Fair, and sometimes Bair); and UpB because it's called Fortress for a reason. It has invincibility frames. And it's amazing out of shield (or OoS to use a bit of Smash jargon you may or may not be familure with).
Oh yeah, and Bowser's shield is GIGANTIC. Please use it. Bowser was built take the blows and pummel when they foolishly get to close.
Other than that, read the stickies. The epic guide thread is nice, mostly a quick run down of Bowsers moves and what you should generally do with them. And the grab thread is nice to read up on if you have time to prepare for a paticular match. For instance, if you can grab Wario, congradulations, you have yourself a fat little italian man you can use and abuse as you please... although, you have to actually grab him which is nigh impossible if they know what they're doing.
But don't worry too much about dodging though. Spot dodging with Bowser is pretty laggy you really shouldn't bother with rolling as UpB can do the same thing... only it's an attack with invincibility frames.
But yeah, stickies and shield. And the vid thread. Some nice stuff in there.
Bowser King