If you had in a triple battle Pokemon with the ability Plus in the middle and two Pokemon with the ability Minus on either side. Would the middle one get a 2x S.attack boost? and would both the Pokemon on the sides get the S.def boosts?
Tested it and with some research. I've found that it Does in fact stack so it's like a nasty plot. And I'm pretty sure that everyone get the double S.Atk boost. BTW, Why would the pokemon on the sides get S.Def boosts?