Porygon-Z is my favorite Pok'emon! Before I discovered IVs and EVs earlier this year, I had had the same one since 2004 from Leafgreeen version, but then I bred it to get the one you'll read about below!
Dart the Porygon-Z (I also used to have a lv. 100 Doduo named Deedo, and when they battled together I called them "Dee-dart")
Timid (+Speed, -Attack)
EVs: 252 in SA and Speed, 4 in HP
This Porygon-Z is built to out-speed most Fighting-types and change into a Ghost-type via Conversion, therefore making it immune to Fighting attacks. Adaptability boosts Tri Attack pre-Conversion and boosts Shadow Ball after use-Wise Glasses is held to boost the move that isn't already boosted by Adaptability and allows Dart to hit like a truck! Also, if you're facing a Ghost-type, use Shadow Ball without using Conversion to be immune to their STAB and OHKO them! Wonder Room is used to make Specially-Defensive walls vulnerable to Dart's STABs.