Donkey Kong Jr.
Donkey Kong Jr. (sometimes referred to as DK Jr. or just Junior) is a Kong character that debuted in Donkey Kong Jr. as the titular hero, who had to save his father, Donkey Kong, from Mario. He is implied to either be the current Donkey Kong as a child or his father.
Donkey Kong series
Donkey Kong Jr.
Donkey Kong Jr.'s premier appearance is in the eponymous Donkey Kong Jr. He is the star of the game and the only playable character. It follows the events of the original Donkey Kong, where Donkey Kong Jr.'s father, Donkey Kong has now been locked up by Mario. Donkey Kong Jr. must travel through four stages, climbing vines to ascend them and then watching as Mario hauls his father further on through the game.
There are numerous enemies that Donkey Kong Jr. must avoid. However, if he drops fruit on the enemies, they will be defeated. Once Donkey Kong Jr. has put a key into the cage, Mario will move further on. When Donkey Kong Jr. beats Mario at last in Stage 4, Donkey Kong and Mario both fall; Donkey Kong Jr. catches his father and then walks off-screen with his newly-freed papa.
Donkey Kong Jr. Math
One year later, Donkey Kong Jr. made another playable appearance in the game Donkey Kong Jr. Math. His father stood at the top of the stage, holding a sign with a random number placed on it instead of being kidnapped by Mario. Donkey Kong Jr. had to climb amongst multiple vines to gather the correct numbers and mathematical signs to create the number on his father's sign.
This game also starred a pink-colored pallete swap of Donkey Kong Jr. that could be playable in a two-player game; however, Donkey Kong Jr. was still brown in color, and could be played as in both one- and two-player modes.
Donkey Kong (Game Boy)
In Donkey Kong on the Game Boy, Donkey Kong Jr. teams up with his father to kidnap Pauline, and Mario must defeat both of them before rescuing her. For most of the game, Donkey Kong Jr. usually stays in areas inaccessible by Mario, activating and deactivating levers in ways that can either help or harm Mario. Sometimes, Donkey Kong Jr. even appears out in the open and throws Poison Mushrooms. He defeats Mario instantly if he touches him. Finally, Mario got to stop him for good in Stage 9-4, where he locked him in a cage in a fashion similar to Stage 4 of the original Donkey Kong Jr.. In the ending, Donkey Kong Jr. somehow managed to free himself and lay in wait as Pauline gave Mario a Super Mushroom to catch Donkey Kong, and acted as soon as his father was calling for help, although they presumably buried the hatchet.
Donkey Kong Country: Tropical Freeze
Donkey Kong Jr., voiced by Frank Welker, is featured as the main protagonist of the cartoon short Donkey Kong Junior from the animated series Saturday Supercade. Here, Donkey Kong Jr., after discovering his father is missing from the circus, decides to track him down with the help of a clumsy biker named Bones.
Nintendo Adventure Books
Donkey Kong Jr. makes an appearance in the sixth Nintendo Adventure Book, Doors to Doom; in the book, Mario and Luigi find themselves in Donkey Kong Jr.'s jungle after entering one of the doorways created by Dr. Sporis Von Fungenstein. Upon seeing Mario and Luigi, Donkey Kong Jr. attacks them, forcing the two to flee. Eventually, after a vine-climbing chase, the Mario Bros. escape Donkey Kong Jr.
Super Mario Kart
In 1992, Donkey Kong Jr. appeared as a playable character in Super Mario Kart for the Super Nintendo Entertainment System. He was classified as a heavyweight character alongside Bowser. His preferred item was the Banana, with which he would litter the racecourses. His kart had maximum top speeds; however, if he were to drift away from the main course, its speed would decrease greatly. In every Mario Kart title since Mario Kart 64, he has been replaced by the modern Donkey Kong. Nearly identical look-alikes also appear as a cameo in the background of Waluigi Stadium in Mario Kart: Double Dash!!
Super Mario All-Stars
In the Super Mario Bros. 3 remake in Super Mario All-Stars, the Mushroom Kings are turned into different creatures than in the original. The Big Island King gets turned into Donkey Kong Jr. This happens in other 16-bit remakes of Super Mario Bros. 3, including Super Mario All-Stars + Super Mario World, Super Mario Advance 4: Super Mario Bros. 3 and Super Mario All-Stars Limited Edition.
Mario Tennis series
In 1995, Donkey Kong Jr. appeared as a playable character once more – this time in Mario's Tennis. He appeared as the only large character in the game, for Bowser was not playable.
Mario Tennis (Nintendo 64)
Donkey Kong Jr. also made an appearance as an unlockable playable character in 2000, in the Nintendo 64 adaption of Mario Tennis. He was classified as a Power Character, who could be secretly unlocked (alongside Shy Guy). In this game, Donkey Kong Jr. is unlocked by winning the Star Cup in Doubles. Also, his default doubles partner in this game is Donkey Kong.
Game & Watch Gallery series
Donkey Kong Jr. appeared many times in the Game & Watch Gallery installments. Donkey Kong Jr. appears in the first two games with role as a "damsel in distress" in several of the minigames. However, Donkey Kong Jr. is the star of his own minigame which is a small remake of the original Donkey Kong Jr. Game & Watch game. The same minigame from the third game also appears in the fourth installment of the series.
Super Smash Bros. series
Super Smash Bros. Melee
Super Smash Bros. Brawl
In Super Smash Bros. Brawl, Donkey Kong Jr. did not return as a collectible trophy, though data extracted from the disc shows that he going to appear but was scrapped. Instead, he has a Sticker. The sticker shows Donkey Kong Jr. with a key over his head; the sticker is only referred to as Junior. It raises launch resistance by twenty-one in the Subspace Emissary adventure mode of the game. His other sticker shows him holding a tennis racket from Mario Tennis. Additionally, one of the names that appears when the player presses the "Random Name" button when naming their custom stage is DKJR.
Punch Out!! series
Super Punch Out!!
In the second arcade (and second overall) game in the Punch Out!! series, Donkey Kong Jr. could be found in the audience again, along with Mario, Luigi, and Donkey Kong, this time with a different color scheme.
Donkey Kong Jr. appears as a participating racer and an opponent to Mario in the Super Mario Kart adaption in one of the volumes of the Super Mario-Kun.
Trophy information from Super Smash Bros. Melee
Super Smash Bros. Brawl Sticker Information