Am I the only person that finds ganon ridiculously easy to pick up? As long as you know how to shffl you have down pretty much every basic tactic. Fair to keep characters at bay, jabs after an lcancel, and uairs to intercept aerially. He really has no combos. He is basically good spacing, mindgames, and an overall defensive tank.
His advanced tactics take minimal practice that require no finger speed and little timing practice such as ledgehops, infinite ledgestall(not even needed), and spacing for the uair spike. All the rest is just simply mindgames. And the great thing is that most mindgames carry over between characters. So if you know how to play other characters that use basic shffles, ganon is a real simple pick up.
Sheik would be another character most people can pick up as an easy secondary just cuz she rocks the tiers so solidly. But to be truly good with her takes a bit more practice that some might think, especially when facing space animals who know how to handle Sheik. She has a couple of advanced tricks like needle cancels, but other than that her combos just take practice to get used to knowing when to do what on who. She is rather basic.
I dunno what it is about Peach, but I never found her that easy to play really, especially if your opponent has an easy time dealing with turnip spam(like the marios, or someone who can catch turnips without effort)
Marth is really easy to do well with as long as you are superior to someone in mindgames, but if you are equal or behind, I find Marth easy to punish. There is more to just edgegaurding when people get better at things like Di, walltechs, or just use characters that can't be edgegaurded. His combos take a lot more work than say Sheik, and his short hop double Fair did take a bit of messing around with. I think he requires a good amount of skill at a medium level.