Can i ask this obvious question with an obvious answer? Even with the 3.5 tweaks, is Game & Watch still the holder of the strongest Up Smash?
-Up Smash
--Damage decreased from 23 to 21. KBG increased from 96 to 100.
--IASA increased 39 -> 44.
In terms of knockback at 0% on a character with a weight of 100, G&W's uncharged Up-Smash (5221 kb) is barely outclassed by Lucas's uncharged OU Up-Smash (5245.2 kb). They're the strongest single-hitting Up-Smashes in the entire game by an overwhelming margin, but if Up-Smashes that hit multiple times are considered, Captain Falcon's uncharged Up-Smash gets rather close (5156.4 kb) while Ganondorf's uncharged Up-Smash (6301.6 kb) easily outclasses everything.
At 100%, G&W's uncharged Up-Smash (19627 kb) becomes quite a bit stronger than Lucas's uncharged OU Up-Smash (18909.2 kb). Ganondorf's uncharged Up-Smash (18061.6 kb) falls off here, but the sweetspot of Pikachu's uncharged Up-Smash (21262.3 kb) and the hitbox of Ike's uncharged Up-Smash near the apex of its swing (20116.4 kb) become a lot more powerful.
In case you were asking about damage, I've compiled a list of the amount of damage that each characters Up-Smash is capable of.
[collapse="All uncharged Up-Smashes listed by highest potential damage"]Successive hits with the same damage are put in parenthesis (damage * amount of hits) to keep things less cluttered.
41%, Ganondorf [22 + 19]
32%, Bowser [20 + 12]
30%, Lucas [with OU]
30%, Sheik [17 + 13]
27%, Ivysaur [9 + (1 * 18)]
22%, Dedede
22%, Ice Climbers [11 + 11]
22%, Ike
21%, Captain Falcon [8 + 13]
21%, Mr. G&W
20%, R.O.B. [4 + 16]
20%, Roy [(2 * 4) + 12]
19%, Peach
19%, Pikachu
18%, Donkey Kong
18%, Samus [(3 * 4) + 6]
18%, Snake [4 + 14]
18%, Wario [(2 * 5) + 8]
17%, Fox
17%, Link [4 + 3 + 10)
17%, Lucario [8 + (1 * 3) + 6]
17%, Luigi
17%, Mewtwo [(1 * 7) + 10]
17%, Olimar [using Purple]
17%, Squirtle [3 + 14]
17%, ZSS [3 + (1 * 10) + 4]
16%, Charizard [5 + 11]
16%, Pit [(3 * 2) + 10]
16%, Sonic [2 + 14]
16%, Yoshi
15%, Diddy Kong [(2 * 2) + 11]
15%, Kirby
15%, Mario
15%, Marth
15%, Toon Link
15%, Wolf
15%, Zelda [(1 * 11) + 4]
14%, Falco
14%, Jigglypuff
14%, Ness [2 + 12]
12%, Meta Knight [4 + 3 + 5][/collapse]