OK. I'm gonna tell you guys how to fight him in a really simple manner. Start out by doing massive fireballs to approach. There are some things that are really good about fireballs especially against Dedede. One is that they have a good speed for you to follow them which is something characters like Falco and Pit can't do. Second is that it forces some sort of reaction. It can be him shielding, hitting it, getting hit by it, it doesn't matter. It's something that he's will have lag on. While making an opening use things like ftilt, utilt, dthrow, etc to get him open and preferably above you. Once he's above you, stay in and don't leave. Comboing properly can definitely get him to at least 60% with one long string of hits. Now unfortunately, he has some things that can stop us from starting combos like inhale, his broken bair, or his broken grab range. On top of that, his waddles can hinder our fireballs a bit, but not enough to stop them of course. Remember that Mario is so much incredibly faster than D3. Once he gets in, he is gonna stay in for a bit. A piece of advice for this MU is don't rely on your shield. If you shield and he doesn't land a hit on you, he gets a free grab. If you see an attack coming then PS it and punish but don't use it at any other time on this character. Getting a reliable kill move on this guy will be a pain. You can get punished for not perfectly spacing Fsmash and his extremely heavy weight will stop Usmash KOs. He can easily get KOs on you though and at low percents.
I still think this is 60:40 Dedede. On the other hand about MUs, he says that he goes even or actually beats Lucario. I'm a little tentative about him winning right now, but I can agree with even.