Dedede shares the same birthday as Kirby as they both debuted in Kirby's Dream Land. He needs to be wished a happy birthday, too!
The waddle dees that reside in Dedede's castle definitely wish him happy birthdays big-time every year. Kirby does, too, of course!
And to clarify, I headcanon that Dedede doesn't actually share the same birthday with Kirby in-universe, but they do outside of universe! So he's getting wishes now, too.