CD event: evo vs power up
Most of these pokemon that have their community day moves are pretty freaking rare, even with Tyrantiar being a tier 4, it hasn't been easy to power up all six of my SD tyranitar, and even more difficult for the 10 meteor mash metagross, most of which haven't even gotten a single candy yet because of how scarce they are in the wild.
So I got to thinking for debatable the two best CD movesets beldum and Larvitar that also are very rare outside of certain biomes and how to use the candy from the event. (those are being considered as all the other CD pokemon have special circumstances, outrage being better on dragonite than DM, and DP ampharos is sadly not good for offense, with the other event moves being held by nesting species). In most senarios (ie not getting a very high IV catch/egg hatch beldum or larvitar prior toon the CD event) would it be better to use the candy from the catches and trades of the pseudo legendaries if one already has a sufficiently large number of them. Yes these pokemon are exceptionally powerful, and having numerous ones of them might seem like the go to idea. But speaking from experience having a huge number of them that wont be powered up for a while (only 2 of my tyranitar have gotten candy since, while a few metagross got candy from the trades) doesnt exactly mean they will fit for raiding for some time. Its not like gengar, where you can get as many as you wanted from the raid day and still be able to power them up with ease because gastly is somewhat common, similarly for the starters being nesting species allowing easier access to candy.
Its an interesting senario, (assuming one doesnt have 500+ candy prior to the event) either mass evolve and not be able to power up for a while or evolve a few and have a very high level force of these event move pokemon very soon after for immediate use. Its not exactly one side or the other, everyone has different limits on candy and what they'd want to power up/evolve. And the addition of trading and being near the holidays likely will mean more distance trades that could also lessen this candy problem for larvitar and beldum.