Well, I haven't had time to really go out there to tourneys lately due to school, but out of all the common matchups so far that I've faced as Shulk, right now the hardest ones for me are:
<- It's hard. He combos Shulk for days, once he gets close to him Shulk has a hard time getting Diddy off him. Seems like a match where we need to punish the mistakes the Diddy is making through perfect DI and hitting back using our range. At higher levels of play, this just becomes harder and harder. At least our attacks can swat away banana peels.
I'm glad I also play Fox, I have a much easier time with Diddy (feels even, IMO).
<- This is probably my worst matchup. Yoshi is really stupid this time around. Super armor on double jump is much stronger, not even Shulk's strong
blade hitboxes break it: I have a recording (I'll upload later today) of an online match where I hit Yoshi with BOTH the
blade hit and
beam meteor smash hit of the D-air and he just kept jumping through it. And his air game. Oh my gosh his air game is incredible. Up-air juggles for days.
<- All the buffs to his attacks make it very risky to trade with him. You have to space super well, and DI the knockback in his moves perfectly (otherwise, you get combo'd to no end until you're in a tough position off-stage). Really hard to figure out what he is going to do with all his Spin Dash cancel mixup shenanigans. Another matchup I find tough with Fox, though I actually feel more comfortable playing Shulk in this one. Personal preference