You cant get 255 EVs. It must be a glitch of some sort, or a hack. The max is 252, as you know. It's impossible withut hacking, or using the AR. No other way. Whatever Pokemon you sw with 255 EVs is hacked somehow. I'm sure of it. As long as the EVs effect the stat points, then it's hacked or glitched. You can obviously have a lot more EVs, but it can't effect your stats unless it's hacked or glitched. Yes, it does say that, BTW. 252 EVs are the max EVs you can have when it effects your stat points. So, to wrap this up, yes. You can have 255 EVs, though remember this. The last three EVs will NOT effect your stats.