Goomba's are enemies in the mario games that have been present in every mario game, with the exception of Donkey Kong, Donkey Kong Jr., and the original Mario Bros. They are fairly simple to defeat in most cases because all that is needed to kill a goomba is to jump on it, but in some cases they can fly or even shoot fire balls.
A goomba is a very simple creature. They usually walk in one direction and when they hit a wall they move the other way. They can kill you if you walk into one, but when you jump on them they dissapear. They look like mushrooms, have two feet, eyes, an eyebrow and a mouth with two teeth that resemble fangs[Source]
In New Super Mario Bros. UEdit
In several trailers Goomba's have appeared so Goomba's will most likely be featured in the game.