To add to this, look at your opponents habits. What attacks do they favor the most. How do they get up off the ledge? Do they roll, stand, or jump? Does your opponent like being in the air a lot? If they do, do they approach you from the air? If so, shield and punish. If they approach on the ground, you're more likely to be grabbed if you're blocking often. There is basic knowledge that you can look at, and then there is match up knowledge. If you don't know the match up, just try your best. If you know what to expect from specific characters, chances are that person using the character will play in the current meta game.
So far, I've noticed that whenever I come across an Inkling, they like to throw out their bomb first. When they want to ensure a kill, they'll go for a roller so they can ground you and do a smash attack. The Wolfs I've come across so far like to use their Blaster in the beginning. It goes far an is annoying. Young Link likes to shoot a fire arrow when he's offstage at an attempt to keep you from running off and edge guarding him. It's things like that. Once you start to learn, you'll become better against certain characters. Needless to say, there are a lot of annoying characters online who love to play keep away, so you might want to invest sometime learning a character who can strike from a distance. And if I recall correctly, you have Richter Belmont. He and Simon are annoying, but if it gets the job done, then take advantage of it.
