The only real good player that I play mains kirby and I'd say the matchup is pretty even. We usually always get above 100% on our last lives but he usually wins. I'm not sure if it is simply because we've been playing together for 2 years, so we know the others tricks, or if it is the MU.
My usually plan of attack is to try to camp out and not do anything risky until I'm above 40%, mostly because of his kirby grab combos. I can usually bait him into approaching, but his bair is pretty fast and has good range so he sometimes can hit me with it as I'm releasing an egg. If you are getting back to the stage, do not try to attack him, he should beat our attacks every time. If you attack him offstage at all, only do it when your chasing him, never when he's chasing you. He can also duck grabs so never run grab him only pivot. Also, to make sure he doesn't miss our second grab, you can always do a down tilt after your first jab and it will always hit, usually causing more damage and cause a possible trip. You can try to throw eggs on the ledge but be careful because he can easily kirbycide you from that position. Also, when approaching with our bair, it can stab if their shield doesn't start close to fresh but, if they are able to shield it all, they can get an easy grab on you or counter attack. Egg lay is not too effective because it is hard to grab him and his lightness usually allows him to fly away, making it hard to hit him while he is in the egg.
To kill him is usually the hardest part. Though he is light, he can usually dodge most of our killing attacks. Some of the ways I usually kill him is with uair, u-smash , and down b. With u-smash and uair, the easiest way is to hit him with an egg when he is close and the hit him with either while in hitstun. However, because the distance is so close, if the egg misses, kirby can start hitting you, making it very risky. Also, down-b is also very effective becuase if you can spot dodge a grab you are able to do a down-b and start killing him somewhere around 125% to 150%. Lastly, with him being so light, a dash attack can kill him, depending on stage location, from about 150% on, though it is also risky. I'm not saying those are the only ways to kill him, those are just the most effective I've found.
In conclusion, I believe that, in a best case senario, it is a 50:50 matchup, but I don't think it will ever be in yoshi's favor and can get worst from there, such as a 55:45 with the advantage to kirby.
