In short, Dedede is not really a good person. He's not the worst person in the world, but you could certainly do better than the guy who likes to order others around and only does things for personal gain. A self proclaimed king that no one respects (and those that obey without question only do so out of fear), King Dedede is the main antagonist of the Kirby's Adventures series, but essentially affably evil. His schemes are always hairbrained and the only reason he does what he does is either for personal gain (food, riches) or as a direct counter to Kirby, who constantly gets in the way of him achieving his desires. Dedede is really nothing more than a big bully, but will go to any lengths necessary if he must, such as using giant mechas on occasion, or relying on his connections with the stronger citizens of Dream Land, like Kracko and Meta Knight. Nothing he does is truly all that bad until the end of the Kirby's Adventure series, where after a final showdown with Kirby, he finally admits defeat and begins a change in his ways as the series ends with it starting the Dark Matter trilogy.
In Alternate Universe, Dedede is much more neutral, due in part with the fact that the series is at the least post Dream Land 3 (though otherwise unstated due to the floating timeline and also alternate continuity), and also because there are now bigger threats than him. In addition, Alternate Universe doesn't have the same plot structure as it's not an action based series, despite having action stories. Dedede simply minds his own, though he's still prone to mischief here and there. Afterall, old habits die hard. Everyone still disrespects him in this series, however. Dedede leads the Academy of Evil in Alternate Universe, an organization of big bads and arch-nemesis-es across multiple series. He came up with the idea simply because he wants to rule the world, not necessarily to induce suffering upon the rest of the planet, but just to be able to freely do whatever he wants without consequence, proving that once again, his end goal is just satisfying impulses. He feels, however, that with a united front, he may finally be able to live in such a world where he can do as he pleases. It may be short sighted, however, because even though Dedede himself may not be evil with a capital E and just wants to go to the theater and help himself to the snack bar, all without paying, the other baddies might try to enforce their much harsher ideals of a world without resistance, and I'm preeettty sure Dedede wouldn't be for a lot of that.