So, here is something I wrote to one of my fellow ICs mains about improving without having to playing against other people. I felt like posting it here.
"[...]Yeah, I know that feeling. The scene in Denmark where I'm from isn't really that big and I live quite far away from the other active smashers (and most of them dislike ICs too, haha), so I have to do much of my training alone, which kind of sucks. Luckily ICs is one of the few characters where you can actually gain a lot from practicing on your own.
Consistency is IMO one of the most important skills in smash. Being able to do what you what to do 100% of the time is so important. What makes a player such as Armada so great is that he's able be get away with his big combos pretty much every time without messing up. It doesn't really matter what you're practicing as long as it's something you think might be relevant in a real match. When I'm practicing on my own I usually focus on stuff like different kind of wave dashes (WD OoS, WD OoS after shield stun, short WDs, long WDs, WD into CC/desync/smash/grab/jab/SH-AC-uair), different types of desyncs, shield dropping, wave landing into stuff (platforms/ground), ledge-dashes, running SH-AC-uair, and wobbling set-ups. The main reason why I'm arguable the best ICs at wobbling today is because I've practiced it so much on my own. Being able to do something consistently boosts your confidence in real matches too, which is a big deal. A missed ledge-wave or wobbling set-up can make you feel horrible after the match. However, a successful 0% -> KO hand off is something that can make you win a game because of the momentum you gain afterwards (hand offs are something you can practice on your own as well).
However, you can't be successful without playing against other players too for a lot of reasons. In today's meta game match up knowledge is really important, and it's really hard to figure a match up out without playing it until you reach a certain lvl of game understanding, and even then really playing the MU can make a big difference. It's also really hard to gain a better understanding of mind games (baits and reads) if you can't get to play against actual people. When I try to get better I think a lot about the game in order to improve my understanding of the game ("Perhaps this could work out in this situation. What can my opponent do in order to stop me from doing this?" and stuff like that). I also watch a lot of matches on youtube trying to figure out why the players make the decisions they do. You can't just watch matches in order to improve. You have to focus on the right things, which can be really hard if your understanding of the game hasn't reached a certain lvl.
Being able to recognize patterns in the other player's play style is also super important, especially for ICs. The climbers are not really mobile enough to play reactively compered to characters like Fox/Falcon. Because of this ICs has to play more proactively in order to get openings which can work out thanks to the character's great punish game. One of the reasons why a player like Wobbles is so successful despite not playing a top tier is because he is really good at recognizing patterns and is able to place his hit-boxes in the right spot at the right time.
One last important skill for a smash player is his ability to control his emotions in the heat of the battle. Even though you might be a really smart player with excellent understanding of the game and your tech skill in flawless, you might still lose to a "worse" player in tournament if you get upset during the match and can't play as well as you are able to win on paper which is another reason why tournament experience is really important.
Smash is pretty much all about game-understanding and consistency IMO. Your game-understanding makes you do the right decisions, so if your game-understanding is great and you can do what you want to do 100% of the time in the tournament setting then you should win (unless you play a bad MU, but that's besides the point.)"