I watched the first two matches, so I'm basing what I say off of that.
Young Link's down air is usually not a good approach option. You use it far too much. It does seem to work on your friend somewhat, but it won't work on more skilled players. Also, you miss a lot of L-cancels. You need to L-cancel all of Young Link's aerials to utilize his speed; it's one of his attributes, so you need to make full use of it.
When playing Falco, you need to make sure that you edge guard that fool well and get the kill. Falco is way better in the neutral game than Young Link, so you need to make the most of every opportunity when he is off the stage. Try grabbing the edge and then coming up with a neutral air (grab edge, press down on control stick, immediately double jump and nair back onto the stage). The back of the hitbox will clip your opponent and you can use ledge invincibility frames if you time it right.
The boomerang. Don't throw the boomerang when Falco (or any opponent) is in your face. It's somewhat laggy and you will get punished. A good way to use boomerangs is to cut off options. For instance, if you have an opponent that likes to approach from the air, angle your boomerang up so they can't do that, and if they do, you get to punish them. But make sure that there is distance between you and your opponent when you throw it.
Use more shffl'd (short hop fast fall L-cancel'd) neutral airs. It's fast, stays out for a while, and has a pretty big hitbox. It's one of Young Link's few good approach options.
I'm not a Young Link main, so take what I say with a grain of salt. However, I do play him occasionally, and I really enjoy seeing good Young Links (Check out the player Axe on youtube). Young Link is a really cool character, so stick with him and you'll have a lot of fun. Good luck and I hope the advice is helpful.
Here is a video of Axe wrecking with Young Link:
http://www.youtube.com/watch?v=Qzfr9iepFgQ