I only have time to watch the Chrom one right now, but will watch the other two later! Here are some things I noticed:
-Chrom is a pretty rush down oriented character, and his air moves come out pretty quick. Almost all of your aerials were done from a full hop, which made your moves somewhat predictable and he would whack you our of the air. Try to mix in some short hops, or do a full hop and then fast fall right afterwards with a Nair or Fair. You can also bait with a jump and go for a grab upon landing instead of using an air move. You can also incorporate tilts, and rarely, smash and special moves with this same bait jump concept! I saw you do this using counter, which was smart, but just use it sparingly. As for your full hop nairs, It looks strange; I think you are lingering at the apex of your jump for too long, not 100% sure on that.
-Your recoveries were usually good, you used Aether pretty sparingly but sometimes had to which was unfortunate. Only use Aether if you REALLY have to. You had good recoveries with Quick Draw, but try and mix it up by grabbing the ledge sometimes, if you land on stage too often it can get predictable. You can even use the QD cancel to catch people off guard when recovering sometimes, but it is usually pretty niche.
-When Chrom came back with invincibility frames, you tried to stall on the ledge using Aether. Sometimes it works, sometimes it does not, Since Ike is somewhat slow it can be difficult to avoid your enemy when they respawn. You can role or air dodge, or simply grab the edge. Just experiment with it!
-I noticed a lot of dodge rolls that were unnecessary, but not too bad! It can be hard online to judge how people are going to approach so I understand this. Either throw out a defense option like a retreating Fair or Dtilt, or just dash the opposite direction.
-Often times you would assume Nair would hit, so you used a follow up tilt which could get punished. This could be lag/buffer but this is probably my biggest problem. I always assume the nair will land when in reality it is just blocked and get punished after a tilt. I'm not entirely sure how to fix this; try and react to if your Nair hits or not rather than throwing out another tilt/aerial attack directly afterwards.
-The majority of your movements were with jumps. While most of Ike's attacks will probably be air moves, work on using your movement on the ground to keep yourself unpredictable. This will not really work on cpus if you are practicing on them unfortunately. Get used to short dashes back and forth, but don't abuse it! In short, spend some more time on the ground, Chrom air moves were catching you many times in the air due to their speed.
Sooo the best way to practice is to get a good training partner either online or off and just go at eachother repeatedly. Identify what you are doing wrong, correct these. With practice, you will be able to do this mid-match and adapt to your opponent's gameplay. If you don't have someone to train with, you can always play online and correct these things, although the game runs so much smoother offline. Hope this helped!