The Smooze is a minor character in My Little Pony: Friendship is Magic. He is Discord's friend who first appears in "Make New Friends but Keep Discord" as his guest to the Grand Galloping Gala.
Though Discord mentions that Smooze is genderless, he's often addressed with male pronouns.
In season 5 of My Little Pony, Friendship is Magic, a new version of Smooze appears in, "Make New Friends, but Keep Discord." But this version of Smooze's completely different from the one in the Generation 1 Series, now it's a green, smily, blob like creature that gets bigger every time it eats something shiny.
When Discord decides to show up to the Grand Galloping Galla, he decides to bring Smooze as his plus 1 in order to show up Tree Hugger. When they get to the Gala, everypony's immediately disgusted when they see Smooze as he slides around the floor, leaving a trail of slime. Then Twilight warns Discord to keep Smooze under control. Then Discord introduces Smooze to Fluttershy and Tree Hugger, trying to get her attention, and push Tree Hugger away from her, but it didn't work. Then Discord neglectfully locks Smooze outside, telling him that he's making him look like a fool in front of Fluttershy.
While outside, Smooze begins to eat the other Ponies jewelry, and starting to grow, angering Twilight and the other Ponies. When Twilight reminds Discord of what she told him, he states, that he, "has better things to do than watch that thing all night", only to jump to control Smooze when he realizes Fluttershy most likely heard what he said.
Then he locks Smooze in a closet, stating that he'll let him out after the Gala's over, but he didn't realize that he locked Smooze in a closet full of gold and jewels. As Discord's giving a terrible stand-up comedy performance, desperate to make Fluttershy laugh, Smooze bursts out of the closet, giant sized, and covers the entire room in slime, unintentionally disabling Princess Celestia's magic.
Then Tree Hugger uses calming noises to make Smooze reform himself, stating that a gelatinous creature like Smooze only reacts to vibrations. With Tree Hugger becoming more popular than ever, Discord gets really angry and tries to banish her into another dimension, preventing Twilight, Rainbow Dash, Applejack, Rarity, and Pinkie Pie from stopping him by throwing a disco ball past them, which Smooze goes after, absorbing them in the process. After he realizes why Fluttershy brought Tree Hugger, and learns the errors of his ways, Discord removes all of the shiny objects Smooze ate, and apologizes to Smooze for neglecting him. Then Smooze Kisses him on the Cheak. Then Smooze and Pinkie Pie get on the dance floor and dance together.