If you are using index and match for this data. Your data is not suitable.

But if this is your data and your request is to find which color is rank first in week 3, you will require some other formula.

To arrange the data to be suitable for index and match. It look like this

1 Wk1 Wk2 Wk3
1 Red Blue Yellow
2 Blue Yellow Green
3 Yellow Green Black
4 Green Black White
5 Black White Red
6 White Red Blue

If you are unable to rearrange your data, the formula that I could provide would be slightly complicated than index and match.