I have a Modest (+Sp.Atk -Atk) lvl 100 Porygon-Z With 252 Sp.Atk and 252 Spd in its EVs. It's IV's are average, but not godly. If you're interested, the IV's are
HP-22
Atk-22
Def-24
Sp.Atk-5
Sp.Def-4
Spd-30
I also have a Lonely (+Atk -Def) Lv.100 Infernape with 252 Atk and 252 Spd in its EVs:
HP-22
Atk-31
Def-26
Sp.Atk-12
Sp.Def-6
Spd-28
I may have a few other Pokemon but I'll have to check.
Also, the Latios is untouched correct?