I've been looking at the achievements I still need, and many require items released during morostide/alegarten/etc. is there a chance they'll be available this year? are any holiday items annual?

All depends on the holiday. Morostide tends to re-release items some years as well as new items to make things more balanced. If the items are very very common and are already cheaply made available then chances are they might now show up. Again it all depends on the holidays and the items involved.

thanks! would you happen to know if the same is true for Alegarten?

From what I remember, yes they do release the same items. Though they have a set up in order with the shops rotating (mostly just the wearable shop tends to only be around X amount of hours each day) generally it's the same items every year with new items in stock. If they do plan on retiring items, they will let us know.

oh, good, some of the items are pretty pricey. guess I'll just wait for Alegarten then. thanks again for your help.

save your sP because some Alegarten items just have a really high price to start with. Subetalodge keeps fairly good track of this, but you can also expect Ariel and Amber to change the official prices on some of them this year. They have done this in the past with this kind of shop.