Client Type (ex. PC, Android, Webclient): Windows Client Version (if known. Webclient has no version.): v2.7.1 When did you first notice the bug?: Today Have you been able to reproduce the bug?: Yes Information (include relevant logs, replays, screenshots): Eevee should not be able to learn Happy Hour. Eevee should not have access to Celebrate in SM LC because the Celebrate Eevee is obtained at Level 10. (If applicable) Sources to confirm the presence of a bug (ex. Smogon): Happy Hour: Bulbapedia Serbii Celebrate: Bulbapedia Bulbapedia (the event)
And, I was voicing a LC BP ban for a bugged move, fml. e: Confirming, used Z-Happy Hour Eevee on LC ladder. :/
Happy hour is a japanese event and also a level 10 move. I'm working on a fix for hidden power and LC (and tier checks in general). Can include this into that fix once it's done.
Fixing it with scripts is like a band-aid solution, but it probably would be better fix it elsewhere. Tagging @Strudels for input because I believe there were other instances of fixing legality problems via tierchecks.
I went and "fixed" all the event legality issues mentioned here through the server scripts because there's no estimate on when the next client release will be. It is also planned for several of the Alolan movepool errors to be fixed in a similar manner, but ultimately yes these are all meant to be temporary measures. The root cause of the movepool issues should be fixed through client updates as they have always been.