This is very easy if you use a solver. Probably the best one is
https://scrabulizer.comJust start a new quick match, set your turn time and match time to whatever you want and have an AI opponent on very easy. Then just simply play through the game using the solver and you should have no problem hitting the 225 mark by the time you are done. The achievement won't pop when you reach 225 but will after the match has ended.