Here is the full list of all 15 Boggle achievements worth 1,000 gamerscore. It takes around 40-50 hours to unlock all of the achievements on Xbox One.
You reached the Diamond league. Congratulations!
You are part of the Elite.
You found all possible words on a grid.
You scored more than the maximum points possible. MAGIC!
You can do no wrong (20 correct words in a row).
You finished first in an online game.
Find 3000 3-letter words.
Find 2400 4-letter words.
Find 1500 5-letter words.
Find 600 6-letter words.
Find 210 7-letter words.
Finish first in 100 online games.
Play 500 games online.
Find 80 words of 8 letter or more.
Play 500 classic games.