On the first video:
0:00 - I kept having to restart this video because I had the lyrics to "Snake Eater" in my head while I was listening to the music so I couldn't concentrate on the video.
0:14 - You could have pivot grabbed instead of spotdodging.
0:22 - Work on your chaingrabbing so stuff like this doesn't happen again.
0:45 - You should have tried to cg her across the stage given the percent she was at. If you had, she would've been at kill percent afterwards. Of course, given your previous attempt to cg her, I can understand your apprehension. 1:05 is a more understandable bthrow.
1:25 - See above.
1:36 - Ouch, should've gone for the ledge bro.
2:21 - You could have easily grabbed her.
2:52 - NICE LEDGEGRAB! I also really liked your offstage game leading up to it.
3:27 - Against Peach, be sure to short hop your aerials when she's at that height above you. You miss a bair here and do the same thing later and she punishes you for it.
4:41 - Recovering low is seldom a bad idea against someone who kills a lot with their utilt and usmash.
4:55 on - It seems like from this point on you're too focused on going for the kill and it makes you reckless. If it weren't for the nice save you had at the end, she likely would've won the match simply because she was putting so much pressure on you and had a great deal of momentum going.
Now for the G&W video.
0:24 - You gotta space your aerials better so you don't get punished like this. It happens to me a lot too though lol.
0:28 and 0:30 - ZE UTILTING INTO A SHIELD, ZEY DO NOTHING! Seriously though, don't stale your kill move.
0:46 - PIVOT GRAB.
1:38 - PIVOT GRAB.
2:10 to about 2:20 - Again, you were getting too desperate looking for a kill and you got punished quite a bit for it.
2:44 - PIVOT GRAB.
Overall, you actually did pretty well against the G&W and I'm guessing the reason why you didn't do as well against the Peach is because you didn't have enough matchup experience?
Anyway, your Dedede is very good in the air, but on the ground it seems to really be lacking strength. Generally, I would try to work on that just a bit more, as well as practing your spacing and CG timing.