You say you have trouble approaching reactive characters like Ganondorf and Little Mac. Interestingly these characters have trouble approaching Bowser as well. My guess is the style you're typically seeing is a lot of noncommital jabs, rolls, safe aerials from ganon, fox trotting, etc ... What looks to you like a guy playing really crazy, is actually a guy that very rarely dash grabs, dash attacks rools behind you .. etc. The reason they wouldn't want to do that is that Bowser's jab, and pivot grab beat all their options.
These matchups tend to involve a lot of Baiting. What that means is an opponent throws a move out that looks very punishable but actually isn't punishable at the distance you are currently at. For instance a common theme you'll see playing ganondorf is them throwing out what appears to be a completely punishable up smash for no reason. They then immediately throw out an ftilt knowing that you are dashing towards them. You also can bait characters with things like firebreath, autocancel fair/bair etc. . .
At the high level all you'll see is people pretending to approach each other, and throwing out completely safe moves. It's weird.
For projectile characters it's kind of a total different game because you have to approach. First you need to have you perfect shields on fleek. Next realize that there essentially two games. 1 when you are like half a screen away, which is basically shield walking or dashing until you get close. Once you get close enough to dash grab it's a completely different game. They will change their behavior and whatever they choose to do can be punished. For instance a link might choose to start jabbing and then roll. You can then just punish the roll. Or a samus might use his tether grab to get you at full distance. Spot dodge and fsmash. The most obvious option which is just dash grab, is usually the worst at option because they are expecting you to do it. Just wait at that range and let them reveal to you how they like to play when panicked. Then exploit that for the rest of the game. At some point you might get them so confused that they start shielding. Then you can pull out the dash grab.
