In super training, you would notice 3 things:
-> The small turquoise shape in the middle
-> The yellow bars outside of that
-> The overall hexagon
The aqua shape is supposed to be the Pokemon's base stats. You can check it out yourself, compare a legendary's shape to a much weaker Pokemon.
The yellow bars are believed to represent EV's - or so I think.
The hexagon I believe is just a guideline to show where each of the stats are placed. If a Pokemon is fully EV trained with a high base stat, it is possible it will exceed the hexagon. (Such as shuckle fully EV trained in defenses).
Hope I helped! :)