OK, now for the rest of the characters!
Pit:
Up-slope- No. Falls a little too quickly.
Down-slope- No. Jumps too high.
Ice Climbers:
Up-slope- To tell you the truth, I'm not sure. I need more testing on this one.
Down-slope- No. Jumps too high.
R.O.B.:
Up-slope- No. Fall too far away.
Down-slope- No. Jumps too high.
Kirby:
Up-slope- YES! But it needs to be buffered almost perfectly.
Down-slope- No. Jumps too high.
Meta Knight:
Up-slope- No. Falls too quickly. (Are you sure that he's chain-grabbable up a slope? He looked like touched the ground way before I could do anything)
Down-slope- No. Jumps too high.
King Dedede:
Up-slope- No. Falls too far.
Down-slope- No. Jumps too high.
Olimar:
Up-slope- YES! Requires a little bit of buffering, though. Not as much as Kirby, however.
Down-slope- No. Jumps too high.
Fox:
Up-slope: No (duh...). Falls WAY WAY WAY too quickly.
Down-slope: No. He falls too far away despite being the right height for it. o_O
Falco:
Up-slope: No. Falls too quickly.
Down-slope: No. Jumps too high. (lolwut)
Wolf (oh, I can't wait...):
Up-slope: No. Falls too quickly.
Down-slope: No. Falls too far....
Captain Falcon:
Up-slope- No. Falls too quickly.
Down-slope- No. Jumps too high.
Pikachu:
Up-slope- No. Falls too quickly.
Down-slope- No. Jumps too high.
Squirtle:
Up-slope- No. Falls too quickly.
Down-slope- No. Jumps too high, but you can still up-smash him out of it.
Ivysaur:
Up-slope- YES! It's kind of like Falco, actually.
Down-slope- No. Jumps too high.
Charizard:
Up-slope- No. Falls too quickly.
Down-slope- No. Jumps too high.
Lucario:
Up-slope- No. Falls too far.

Down-slope- No. Jumps too high.
Jigglypuff:
Up-slope- No. Jumps too high (lolwut), but you can now up-smash her out of release.
Down-slope- No. Jumps too high. I didn't test the grab-release to u-air, however.
Marth:
Up-slope- No. Falls too far.
Down-slope- No. Jumps too high.
Ike:
Up-slope- No. Falls just a little too far.
Down-slope- No. Jumps too high.
Ness:
Up-slope- YES! And you can even up-smash and dash attack him out of release.

Down-slope- No. Jumps too high. I didn't test the grab-release to u-air, however.
Lucas:
Up-slope- No. Falls too quickly.
Down-slope- No. Jumps too high. I'm not sure about u-airing him, though....
Mr. Game & Watch:
Up-slope- Actually, I'm not sure. This guy NEEDS more testing. o_O
Down-slope- No. Jumps too high.
Snake:
Up-slope- No. Falls too quickly.
Down-slope- No. Jumps too high.
Sonic:
Up-slope- No. Falls too quickly.
Down-slope- No. Jumps too high.
So...
Characters that this is effective against: Sheik (down), Kirby (up), Olimar (up), Squirtle (down), Ivysaur (up), Jigglypuff (up), Ness (up)
Characters that require further testing: Wario (up & down), Ice Climbers (up), Mr. Game & Watch (up)
Character that ONCE AGAIN gets screwed over by grabs: Ness
