This is achieved by coming 1st (out of the 2 teams) for each of the 10 races under Team Vs Team (which can be found under World Tour Events>Team Vs Team).
Seeing as just winning will not be enough (wasn't for me for the last 4 races), it would be wise to (literally) take out the opposition in order to help your teammates get higher positions. You can of course just win and hope your teammates achieve higher positions (but come on, it's A.I. why would they help you?!)
Like my brief guide for Team Battle, best to wait (if you want) till you are number 1 when you hopefully have a load of bikes to choose from.