I'm still not sure about what we should do with Encored Sleep moves and Magic Coat. It is true that it's not completely the sleeper's fault, but not limiting them could be really easy to exploit.
That's because the Rest user chooses whether to sleep or not. If Effect Spore activates, that's just an advantage for the Effect Sporer. Sleeping another Pokémon afterwards should break the rule.
However, the user that accidentially put a pokémon to sleep due to Effect Spore couldn't choose which Pokémon he put to sleep.
It could happen that he wanted to put his opponent's Scizor to sleep because it was a giant problem for his team, but accidentially put Swampert (which wasn't a problem at all for his team) to sleep when he switched in his Breloom. Bit of a mixed bag, again.
Also, if we say that non-clausebreaking moves will count as a first sleep, then Rest would become an exception of an exception. It could be easier to just say that ALL non-clausebreaking moves don't count as a first sleep, to keep things simpler.
By the way, Secret Power can't put anything to sleep in a Wi-Fi battle
I know, but I thought we could mention it just for the list to be complete.
PS. Yawn should be inclueded in the list of sleep clause breakable moves.
Thanks for mentioning Yawn, I completely forgot about it. I'll add it to the list.
Moves that break Sleep Clause when inducing Sleep
-Dark Void
-Sing
-Hypnosis
-Sleep Powder
-Spore
-Grasswhistle
-Psycho Shift (selected with Sleep Talk)
-Secret Power
-Yawn
Moves that do not break Sleep Clause when inducing Sleep
-Rest
-Effect Spore
-Metronome
-Sleep moves used by a pokémon forced to use it (Choice Items, Encore, Inprison, Torment) that is unable to switch out (Mean Look, Shadow Tag, Arena Trap)
Moves under discussion
-Encored Sleep Moves
-Magic Coat
I'll make a poll about it.