Hmm... Here's my list of considered characters: Luigi, Diddy Kong, Ness, Lucas, Wolf, Falco.
Well, I guess Luigi's projectile isn't so good, Diddy Kong's idk, Ness and Lucas have good projectiles, Wolf and Falco are OK I guess...
So now it's Diddy, Ness, Lucas, Wolf, Falco. Of them, which is 'watch out, DDD' material... As I play DDD a lot, I have to say that Diddy Kong is very annoying with his bannas. Wolf and Falco aren't too anoying, so I'll take them out of the picture. Ness and Lucas's thunder can be very annoying when they juggle you with it.
So what's left is Ness, Lucas, and Diddy. Although Wolf, Diddy, and Luigi had a lot of potential when Brawl came out, I'm gonna still take Wolf and Luigi out since they don't really give hard times to DDD and don't have such good LONG range projectiles.
Looking at how the post said something like: This hint was influenced by looking at htese sources... On the character match up chart, it says Diddy, Ness and Lucas have advantages against DDD. On Ankoku's character rankings list, Lucas, Ness, and Diddy seem to be doing pretty bad. So, I'd say that they all fit the description. I think these 3 chars had a lot of potential since the beginning... I can't decide which of them it is.
Diddy, I think, seemed to have the most potential since the start. But I don't know much about his projectile game. Diddy doesn't have 'a suprisingly good ability to KO', although he is strong for a fast character. Ness and Lucas's smash attacks, like the bat, surprise me quite a lot when i see how powerful they are. Lucas's up smash scares me. Diddy's game can be 'situational', since his bananas could be 'situational', since it depends where he puts the bananas. So I guess it's either Lucas or Diddy. Lucas can be chaingrabbed (i think, idk if he falls), but i know he can be infinite chaingrabbed by Marth, so that could be part of the 'situational' thing. I guess I'll have to say Lucas, just cus his long projectile game is better than Diddy Kong's. Diddy, although his bananas are annoying for my DDD, I think fighting him is pretty easy since his attacks have short enough range that DDD can ftilt, or grab, etc. him.
So my final answer I guess, is Lucas, until further notice
edit: and oh, even more now i think it's not diddy, cus im pretty sure DDD can use his waddle Ds to block his peanut gun thing.