It always takes me a minute to remember how to solve that one :) Here are a couple hints:
Hint 1You have to make a line with two X's and an O, and then send the crab over and through the O. There are a couple ways to do that, but you can't squish your crab or allow the enemy to get 3 O's on the board.Hint 2The crab will move twiceHint 3Move the crab and then make an XOX