This was quite simple once I had worked out what to do! Start by playing a 2 player local game (both on same controller to make it easier). Play as normal buying up all of the streets via auction to ensure both players retain a healthy bank balance and the game isn't finished early. Try to buy 2 properties for each colour for player 1 and get the third street under the second player. Eventually you will get to a stage when there are 2 colours with 2 streets owned by player 1 and 1 street owned by player 2. At this stage initiate a trade with player 2 (pressing Y after you have rolled the dice on your turn) and swap any irrelevant streets for the 2 streets that will complete the 2 street's for you.