While I appreciate your answer, I know this cannot be correct. If there was this simple a pattern, I'd have noticed it by now; I know it's wrong because I have many Pokemon with multiple perfect IVs, but they don't all have the same expression in the Trainer Memo (which your pattern says they all should). Two of my bred Pokes for example:Shroomisaur:
For the purposes of the Trainer Memo message, if more than one Individual Value is the highest, the first Individual Value among them in the order of HP, Attack, Defense, Speed, Special Attack, and Special Defense is chosen. For example, if the Pokemon has Speed and Special Attack IVs of 31, then the message "Alert to sounds" (Speed) is used, not the message "Mischievous" (Special Attack).
Venonat, timid: 31/10/31/31/31/31 Saying: "Somewhat Vain"
Grimer, careful: 31/31/31/05/26/31 Saying: "Likes to thrash about"
I know these IVs are exact, and as you can see the expressions do not follow that pattern. There must be a different explaination, or something else influencing this... sure wish I knew. Any ideas?