Sure! The Porygon evolution Theories are one of my most favorite, so I know a lot about it! Basically, it's like this. You know how each of the Porygon evolution's has something to do with moving through either Cyberspace, Space, or alternate Dimensions? Well, in Porygon-Z's case, it seems that something...wrong, I guess... happened when it was developed. As in the HGSS and Pokemon Y entry says: 'Its programming was modified to enable it to travel through alien dimensions. Seems there might have been an error...' However, since only Porygon has ever been aired on TV and only for EP038, Porygon was never shown on TV again. For that reason, why Porygon2 and Porygon-Z were created afterwards anyways has been floating through myths and questions since. Another thing is what 'error' could have been. Some speculate that the error messed up Porygon-Z's programming, which is why it acts strangely when you use it to attack. There are a lot more theories then this, but this is just the baseline for it. There's also theories how Porygon the one real Pokemon that lives in cyberspace, but I really doubt that. Wow, I just wrote a lot, now that realize it!