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' played 500 online games.
You played 500 classic games.
You found 1500 5-letter words.
You found 3000 3-letter words.
You found 80 words of 8 letters or more!
You found 2400 4-letter words.
You found 210 7-letter words.
You finished first in an online game 100 times.
You found 600 6-letter words.
You finished first in an online game.
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).