i was thinking in terms of a simpler algorithm for division of EXP. take the levels of however many pokemon participated in the earning of the EXP, add them up, and then divide each participants level by that sum. take that quotient and multiply it by the total EXP to find out how much EXP each participant receives

say the total EXP to be earned is 60, to be split between a lvl 8, a lvl 32, and a lvl 12.
08+32+12=52

08/52=.154  .154*60=09.24  so 09 EXP for the lvl 8
32/52=.615  .615*60=36.90  so 37 EXP for the lvl 32
12/52=.231  .231*60=13.86  so 14 EXP for the lvl 12

in this scenario, the higher level pokemon will gain EXP faster, but higher level pokemon also require more EXP to level, so the system has some balance to it...