I disagree with you, as a Shulk pocket, I'd argue that Shulk probably starts off around Mid Tier imo, he's a chara with a relatively high skill floor, but an even higher skill ceiling, his frame data being horrendous doesn't stop him from having several reliable combo/strings such as Down Tilt > Grab > Dthrow > Fair > iirc another grab/dtilt if at low% or Back Throw > Back Slash, that work till 60-70% thanks to Buster extending his combo potential. His long range, while hampered by his mediocre frame data, allows him to stall a bit if he somehow messes up his Art and needs to wait for, say, Speed to reload.
I also need to add that his recovery and edgeguard potential is no joke, Jump Art is a godly recovery, an equally good gimping tool and Smash Art can seal a stock with a D/Bair at around 60/70%. That's no joke either.
Speaking of which, Smash Art gives Shulk an overwhelming advantage, especially when he is at low percents, when it's essentially a no risker, where he can kill with pretty much anything with the most powerful, knockback wise, Smashes in the game (Let's not count WFT, please.), and can allow him to quickly force the opponent into a retreating situation, where he can then take the right measures to punish and kill. Finally, while Defense is a double edged sword, making him combo food till absurd percentages, it's no joke either : It's the perfect tool to abuse rage, force a time out, and force stronger targets such as Bowser to respect you, that range making you kind of hard to approach if used well.
All in all I strongly believe that Shulk has the right tool to combo, kill, pressure and control space comfortably against the lower half of the cast -at least- in the form of Monado Arts, and that, with the appropriate development (And calibrating, I guess, because lets be honest every character is going to get more buffs/nerfs sooner or later.) can even end up knocking at the door of high tier. His room for devlopment is as huge as Robin's or Rosalina's and I'm kinda impatient to see where it will lead him to.