Comment on ESP: Berserker Virus (Scripts) by EV-Zero
So can an infected pokemon with level 3 virus be infected again
They can, but only with another Category 3 virus. After get infected again, he or she becomes Category 3-A. If Category 1 or 2 virus tries to infect them, the Category 3 virus will kill them since 3 is stronger than 1 or 2 when 1 on 1.
And a category 3 infected pokemon with stage 7 can control the acton of category 1 and 2 right
Yup, but only for a limited time