She isn't *that* bad. Bad enough to deserve her current spot on the tier list, give or take a bit.
I wouldn't say she dies easily in general. Off the top, yes.
Her smashes are better than most of her non-kick moves. Her down and forward smashes are fast and more spammable than most smashes in the game are. Zelda's down smash is the fastest smash in the game, and sends opponents at a useful angle (down about 45 degrees). Forward smash has huge range and is fast for a smash.
I'd say the reason Zelda is low on the tier list is because of a lack of mobility. With the worst wavedash, worst run speed, and second slowest jump, she is very immobile. A horrible grab speed, and lack of decent throws or combos doesn't help either.
Both do about 20% with good knockback if sweetspotted. Better than any other moves Zelda has. Sure there are some moves that are arguably better on other characters. But the kicks are really good compared to most characters' f-air and b-air..
Lol, I don't think Fsmash is ness's best move, or that Ness's Fsmash is one of the better Fsmashes in the game... It's good compared to ness's ground game in general though..