Thanks Kirby Wikiさんのイラストまとめ

Artwork of Marx in the Japanese manual for Kirby Super Star seems to suggest that he is wearing glasses. This detail is left out in other artwork of Marx.

before anyone asks yes susie was a catgirl at one point

these are all the same character

Walky is a regular enemy in the Kirby series. He is a living, sentient, dangerous microphone that can't carry a tune for his life.

Japanese-exclusive scene where Chef Kawasaki talks about eggs at greater length.

The appearance of Rolling Turtle is similar to that of a turtle or tortoise. It has bunny-like front teeth along with naive eyes. It seems to have a human-like vertebrae and a very round shell.

In Super Smash Bros. Ultimate, Kirby's copy ability when copying Steve resembles Square Kirby.

In the Kirby's Dream Land artwork, Lololo & Lalala are not wearing their gloves and have arms similar to Kirby. This is not seen anywhere else, including in-game.