If you look at the US website, they ask for paystubs from all years that you have worked in US. I believe submitting a copy of all the paystubs looks good. This helps to match the payments against the W2. Particularly, if you have changed companies inbetween then it is advantageous. In such cases, you might have multiple W2 wages document in a year, i.e., 1 W2 for each company.
