Reading the trophy guide I do not understand this achievement
"You raced for five different teams in Season Challenge in a single season.
You can get this trophy alongside the "Top of The Class" trophy. When you start Season Challenge you have the option of selecting a rival. Pick a driver in any team you know you can beat. Spend two races defeating you rival (best of three races) once you have defeated him, select another rival who is in a different team. Repeat this another 3 times and the trophy will pop at the end of the race once you're in your 5th team."
I tried this but I must have messed it up, what I want to know do you actually have to race for 5 teams or just have 5 rival teams?