The official name of DK's Down-B is "Hand Slap." So what is a hand to slap when the ground is out of reach?
Well, how about the other hand? Conveniently, Donkey Kong had a series of games based in part on putting his hands together, with Jungle Beat in particular turning the clap into a versatile, essential ability. This idea could be translated into the perfect new aerial Down-B.
("Could be" meaning "hypothetically," not "actually possible")
Usable once per airtime (akin to tethers and Ganondorf's Dead Man's Volley), the move would have DK simply clap, creating two soundwave graphics of differing sizes and a variety of effects:
- Coverage – The move provides a hitbox to cover his whole body, importantly his front, with disjoint. The size also allows him to block opponents trying to get past him.
- Clanking – One of the uses in Jungle Beat is repelling certain objects, which could translate into a defense against projectiles. Could be jury rigged into blocking stronger ones while itself being weak by having its regular hitbox be transcendent, with a clankable, lower priority, higher damage hitbox inside of it.
- Absorbing – They were able to add reflectors, so it might not be totally out of the question. While transcendent projectiles would penetrate the above, they are all (sans tranquilizers for some reason) energy-based, so this would stop them. Also PK Fire.
- Item grabbing – Another of the uses in Jungle Beat, the main one, is grabbing bananas. Hence a cool ability would be if holding B could cause DK to pick up nearby-but-still-normally-out-of-reach items. Would be an interesting twist on it stopping projectiles, fix some wonkiness with bombs and gyros, and give the Donkey/Diddy team some synergy.
- Momentum stalling – In JB, Donkey Kong halts in midair while grabbing bananas. This could be translated into some momentum-changing properties, which would monumentally increase DK's potential for creativity and mixups in neutral. Coincidentally, it would also make it mirror another of its uses in JB: dodging certain attacks. Like similar moves, though, if read it just makes DK a big stationary target trapped in the air.
- Approaching – Or rather, adducting. As an extension of the banana-vacuum use in JB, it could have inward knockback, forcing campers toward DK. With set knockback and carefully balanced endlag, it could be used to draw in lighter, more troublesome characters, while heavier characters could use frame advantage to reverse it into their own approach. A windbox on the outer edges would add to this characteristic.
- Shield damage – Another JB-use is to pop banana-containing bubbles, which might be represented by the move having some extra shield damage. Not enough to truly threaten (I imagine it dealing little regular damage, anyway), just to spook. But hey, if DK can get it to pop a shield, then it's also referencing the JB-use of stunning enemies.
- Wall jumping – Not technically a JB-use, although it can be JB-used to create magical bouncy objects, and Jungle Beat is the game that introduced wall jumping to DK's repertoire. The idea is that, if DK is within a certain range of a wall, uses Down-B, and presses away from the wall, the endlag would be replaced by a wall jump. Would provide a slew of new options for edgeguarding and recovering, especially considering his otherwise-limited vertical distance.
Overall, I think even an incomplete version of this move would make DK a much better character, in the senses of both viability and design. It would provide a unique, skillful work-around to some of his weaknesses, and add a lot of depth not just from getting the most out of its uses, but deciding how and when to use it under the once-per-airtime constraint. Moreover, to avoid visual redundancy, his FSmash could in turn become the advancing swing-kick from DK64.