Your approach. RARed bairs need to be integrated a bit more into your approach instead of strictly after the target is in the air.
Your hammer use was terribly predictable after a while. It's also something I see in quite a lot of matches. If you miss the shot, you can count on the same attack being used again within the next 10 seconds in attempts to land the shot you should've had previously. It's a habit I've learned to stop after a while, myself.
Don't forget about Kirby's neutral A punches. When you're both on the ground and close to each other, yet Fsmash won't go for the KO just yet, that attack is actually very useful.
About grabs, though not very common in the match (that could also be looked into), Kirby's down throw deals more damage (I believe it was 2% more) than all others he has, and sends the enemy in the same trajectory as all of the others. So that's the way to go in those situations. Also, remember that you can jab a few times while they're grabbed to build up damage. Kirby's is quite fast, and around the 80% range, you can easily pull 3-4 jabs before each throw. Every hit matters.
Other than that, not bad at all. I do sense a not-so-good Metaknight there, though. Playing against some other Kirby players might help to improve your game a bit, too.