I don't have time to go over this team step-by-step right now (although it looks like DCE's given a pretty thorough analysis already). However, I will note that in my experience, Blissey isn't normally used first, as it basically must switch out when faced with a physical attacker. I'd lead with someone else and, like DCE suggested, throw it into the mix when you're faced with a special sweeper.

I can also quickly answer DCE's one question:

Quote Originally Posted by DarkCyberElf View Post
BTW what is Porygon Z's last move??
Hidden Power, using the Fighting type. HP [insert type here] is common notation around here for that move.