I think it has to do with online mode with the counter, to be honest. I know I am hitting the buttons before a hit but it doesn't even get to make a failed attempt - their hit just comes out first. To do a counter you really have to have that split second reaction and either the move is not fast enough to allow for that, or the online mode just lags - and I'm thinking it is the latter because I don't have problems timing it with the computers. It's rough too because that counter could do a lot to stop the spamming characters, because you can just hug them and the range of his counter should reach no problem.
I am still a beginner with Shulk, but I did recently learn what Buster even did and I was using Smash as my default, so now I'm switching it up. Go Buster first, then switch to Smash at high percentage. I don't even use the other arts. I think Jump is pointless from what I've used of it, and actually helps to mess up short hops than do anything good, speed just increases movement speed and does nothing to speed up his attacks which would have been really useful, and defense... I suppose defense is kinda useful for turtling, like if you have to preserve a stock to take it to sudden death. But in any normal, non-online rules, it's probably pretty useless too. It just stalls the inevitable.