This is an interesting question, since I don't agree with the tier list placings for the low tiers, and the rest of the cast. I don't believe that Kirby is the worst character in the game simply because he has decent moves such as utilt and bair to poke/combo characters, and not to forget to forget uair, which is really good for sending opponents offstage. I would honestly revise the tier list since it has been 4 years since the last one was created.
In my personal opinion, I believe that Roy is the best low tier out of all of them simply because of his movement and somewhat similarities towards Marth. This was a struggle for me since I also believe that Ness is a lot better than what his placings put him as, since moves like fair and bair are extremely good for spacing and pressuring, and his grab game which helps his combo potential. DJC helps Ness a lot, and actually makes him into a decent character, although I tend to whiff moves when doing DJC's.
One thing I can see why people would place him lower is because of his weakness to crouch cancelling and his large sourspot hitboxes, which has little knockback and can allow others to easily punish him for moves like fair if performed incorrectly. I feel like this is a difficult weakness to overcome, but enough practice will allow you to fully utilize Roy's sweetspot hitboxes that are extremely good for combos. Moves such as dtilt, nair, and fsmash are good options to rack up decent percent/kill. Roy's recovery is also easy to gimp, but can actually be angled by performing his normal UpB and moving the left stick towards left/right that can increase his horizontal recovery range instead of his normal vertical recovery. I know this is long, but this again is my personal opinion. Been playing a lot of Roy as a secondary character, and he's a fun character to me. Other characters like Link are great as well, but this thread is focusing on low tiers.