It would help us better if you'd have posted movesets of your Pokemon, and whether you are playing through Wi-Fi (that is, using a 3DS) or through a battling simulator like Pokemon Showdown. If this league is through Wi-Fi, I would highly suggest ignoring the above post, unless you are knowledgeable enough about breeding and EV training, as it is meant for the hardcore competitive battler.
But really, it would help if you provide the Pokemon's moveset, natures, hold items, and, if you are able to determine, its EVs.