Frihetsanka
Smash Champion
His frame data is quite slow, making parries against him a bit stronger (and in general having slow frame data is a pretty significant flaw), he doesn't have generally super easy ways to kill outside of Smash art (which is basically telling your opponent "I'm going to fish for kills now"), overall arts tend to let your opponent know what you're going to do. Oh, and all of his arts have serious drawbacks now (in Smash 4, Buster art had had a really good risk-reward ratio, 13% more damage taken, 40% more damage given, now it's 30% more damage taken, 40% more damage given, so it's significantly riskier to use). I'm no expert on Shulk and other people might be able to add more reasons, this is what I could think of right now off the top of my head.What are those flaws might I ask? I don't really know enough about shulk other than the fact I seen to default to just a select few moves when I play him, and that his jab sucks.
His strengths more than make up for his weaknesses and he's likely either a top tier or a high tier, although I'm not convinced he's a top 5 character.