I decided to make a list of headcannoned voices for Kirby characters! I hope you enjoy :)
Kirby - His voice in the anime / Smash Bros. My headcanons have changed thanks to reading the novels, so he doesn't say poyo here.
Dedede - His voice in the anime. His Smash voice sounds like a dragon, not a penguin.
Meta Knight - His voice in the anime. I can do an OK impression of him actually, but its more of a generic Spanish accent than anything.
BanDanDee - I dunno, but I bet he would have a voice that kind of sounds like Kirby.
Rick, Kine, and Coo - Their voices in the anime.
Marx - I dunno. Maybe he sounds something like Kokichi Oma?
Gooey - Stitch from Lilo and Stitch? It sounds wrong out loud but right in my head.
Adeleine - My own voice. If you say that doesn't count, Hiyoko Saionji.
Ribbon - Himiko Yumeno?
Dark Meta Knight - Meta Knight's Smash Bros voice.
Daroach - I dunno, but for some reason I picture him with a light Russian accent.
Magolor - I dunno.
Taranza - Gonta Gokuhara? I dunno anymore.
Susie - Kirumi Tojo
Francisca - Rosalina?
Flamberge - Princess Daisy?
Zan - I dunno.
Hyness - I dunno.
NOTE: The reason why most of my headcannoned voices are "i dunno" is because, most of the time, I read text in my voice.