Players with good reaction time who know all the options for zoning, defending, initiating or avoiding traps and make very few or no serious technical errors in a match. That is the type of level of play that matchup discussion aims to explain about. The only real mistakes that should actually occur in this level of play should result from coming out of the wrong end of a guessing game trap and very small spacing discrepancies between viable spacing/poke options.
Ganon is an obvious example of being a completely unviable character, since he has no move that beats shieldcamping or spotdodge on reaction, and he's an easily comboed and gimped character. Everyone should agree to this, since that is how his tools actually work. How does he pull off random wins in tournament/friendlies/MMs? Lots of people suck. That's all there is to that really.
Bowser fails less than Ganon since he can pseudo-reliably make someone think twice about shielding or spotdodging, and has something that resembles a decent poke, but his ways to work around conservative play (and projectile camping) are extremely limited, telegraphed, and ultimately quite punishable, and he suffers those weaknesses to combos and gimps and traps in general.
Bowzer's grabs are pretty mediocre at best but if u combine his grab releases with a little wit then the opponent can be in for some serious damage.
Tell me who can't do some serious damage from a grab with a little wit? Seriously.
The GR chaingrab by itself does very little damage if you don't grab someone with your back facing the edge, and even if you do, you're looking at like...20% from pummels for all that trouble...which is decent damage I guess...except how is that even going to happen? Now say you're not really GR CGing so much. Tilts manage to break past 10 damage, so GR -> D-tilt might net you about 20ish%, which is comparable to a standard throw -> followup if usually slightly weaker. Klaw does a little less than 20%. Jab does 5% so Jab Klaw I guess can do about 23%, add maybe two pummels that manages to get to 28% or so, which is probably about the same damage you'll do if you can mindgame in GR -> F-smash. If you are a little ballzy, you might be able to break 30% with enough regrabs/pummels into that stuff I mentioned, which I guess is respectable.
I guess it's alright, but really...is that what you call serious damage for all that trouble?
@Ixis, I'll be pleased to further discuss the Mario matchup some other time.
Like many other players who enjoy this game, I'm here to further the knowledge available for this game and advance the metagame and help improve other players. This is why I enjoy matchup discussion.