I got this on a lightning round, even though the achievement says it must be done in Unlimited or Standard. You can use an anagram solver to help you get this achievement.
Easy way:
Start an Untimed (or Unlimited) game. Go to
http://www.anagrammer.com/ and enter the letters into either the "Your tiles" box in the upper left or the "Get Scrabble Analysis" box a little further down on the left. Click the Go button, and it will give you the anagrams that are legitimate words. Solve the puzzle in Text Twist 2 and go to the next round right now. Repeat.
Lightning Round way:
Start a lightning round. You'll be presented with 5 sets of letters, and you need to create 6-letter words. Every 5 seconds, the game reveals a letter, so if you need help, let it solve some for you. After you've solved the fifth puzzle, you'll get a bonus time added to the clock. The next round is another 5 puzzles of 6-letter words. Do that four times and this achievement will unlock.
Doing this will also unlock
The Bingo Boss achievement in TextTwist 2 (WP) worth 11 pointsComplete only Bingo words in ten levels in a row in Unlimited or Standard. and