Mooses are titular main antagonists in Disney's 1937 short Moose Hunters and minor antagonists in Mickey Mania/Mickey's Wild Adventure video game.
They made their debut in Moose Hunters. That's the cartoon where Mickey, Donald and Goofy tried to hunt down a moose. Mickey hide in the grass, and Donald and Goofy dressed up as female moose, to trick a moose to fell in love in them and then let Mickey to shoot him with a gun. Red Moose was eating grass where Mickey was hidden, and Black Moose was tricked by Donald and Goofy and fell in love with them. Mickey's gun was broken because when he was frightened by Red Moose, he accidently dropped his gun and it broke. When Red Moose ate all grass but one leaf where Mickey was hidden, when he saw Mickey, he gonna mad and wanted to kill him. But he also fell in Donald's and Goofy's mask. Later, Black and Red Moose started to fight about "female moose". When mask fell of Donald and Goofy, they saw that and gonna mad. Donald tried to save him and Goofy when he said that was April Fool, two mooses, chased Donald and Goofy and wanted to kill them. Later, Mickey, Donald and Goofy escaped from mooses by the boat.
Mickey Mania/Mickey's Wild Adventure
Mooses are the titular secondary antagonists of the 3rd level called Moose Hunters, which is named by 1937 cartoon of the same name. In that level, Mickey and Pluto are hunting mooses, and Pluto is pointing whenever moose is going to run, giving Mickey a point to jump to avoid moose. At the end of level, when Mickey found Moose Hunter Mickey, he also find a Red Moose from 1937 cartoon, who is the titular main antagonist of the level. He's chasing Mickey through all the forest, and Mickey is collecting apples to be fast and escape from Red Moose. If Mickey forget to collect enough apples, Red Moose will kill him, which means Mickey lost one life in game.
Also, one of the mooses appears in many of game versions (not in all) in the Prince and Pauper level (during the final boss), when Mickey got help of other Mickeys to defeat Pete. Moose Hunter Mickey blew in the horn (just like in Moose Hunters cartoon and in the game level with the same name), and a moose approached and hurt Pete.