Annal ?
It is biennial.
Biennial -sg that happens every alternate year.
The adjective is quadrennial. (extension of 1-annual, 2-biennial, 3-triennial) (The archaic word for a five-year period is a lustrum.)
Pokemon events happen at random points in a year usually to coincide with a special release.
Annal ?
could it be ENTRY ??
could it be ENTRY ??
Annual means once a year. So, they are once a year events.
Biannual means twice every year.
It means year or yearly for example anniversary this is a Latin root word.
Centenary means the 100th anniversay, which would be the 100th year.
year
While not specifically "by year", chronological means "in order of occurrence in time"
An event occurs 2 times in a year
Biannual.
a century