(everything I'm saying also applies to Whirlwind)
Hmm so
NixHex just posted some of his GSC games, and apparently Sleep Talked Roar
doesn't fail (turn 82). That isn't listed on the to-do stuff (although someone might have mentioned it before, I apologize if that's the case) so I thought I should bring it up since I think it's a pretty important difference from later gens. There might be some other stuff but that's the only one that hit me.
Edit: Really? I was pretty sure it didn't work. Well, don't mind this then.
sleep talk roar is supposed to work in gsc
Not if you are faster. If you are faster it fails.
To clarify the actual mechanic in play here, Roar will fail if it is used before the opponent acts. The usual cases where this happens are a) when Roar is selected by Sleep Talk, and the Sleep Talker is faster, b) when both Pokemon use Roar. a) is mostly crucial to teambuilding, as it's the main reason Roar is not used on RestTalk sets of Pokemon such as Suicune and Zapdos; b), however, affects play as well. There is a c) which can crop up rarely that Curse Machamp may use Vital Throw to prevent phazing.
Currently, b) is implemented somewhat badly; see
here. Currently, it's hacked to make the slower move go first between Roars - this is incorrect in PP-usage and also fails when there's a last-Poke in play - if last-Poke Skarm uses Whirlwind vs. Rhydon's Roar, then
both should fail. a) and c) are not implemented at all, as seen
here.
To fix this properly, the hackjob with slower Roars/Whirlwinds going first should be removed, and a check should be added that IF Roar/Whirlwind is used AND opposing side has not acted yet (move, switch, etc) AND tier = GSC OU THEN Roar/Whirlwind fails.
EDIT: Something I forgot to test; the "fix" currently in place creates a serious error in addition to the minor ones. Vital Throw Machamp should be able to hit a Roaring Rhydon before being phazed, but as seen
here it fails to on Showdown (turn 2). This is specifically an error caused by the "slower Roars go first" hackjob, and not by the failure to put in the proper fix (Roar should indeed work here... but
after Vital Throw hits).