You do realize that Sakurai, the creator of smash bros., is also the creator of the Kirby series? Of course, the enemies are going to remind you of the Kirby series. I figure that these things should be common knowledge of smash fans.
Hal Laboratory is the developer responsible for the Kirby series and was developing the Kirby GCN game. Hal Laboratory also developed Smash Bros. 64 and Melee while Sakurai was a member of the company, but he left to become an independent developer a couple of years ago, before that Kirby GCN game was being created. A completely new company was created with Sakurai heading for the creation of Brawl, but it wasn't being made completely from scratch. A lot of resources Hal Laboratories used in creating Melee were given to this new company. So, it would be no surprise that this GCN Kirby game and Brawl have similarities, but it was Hal Laboratories developing the game.