I'm running Malamar as well, and anyone running Virizion EX, Silent Labs, and some Fairy types completely shut down the affects of abilities, so the sleep part could be voided completely. So that could hurt you... However, if you went the Toxicroak route instead of toad, you can poison them if you can't keep them asleep as you load up Malamar on your bench and still hurt your opponent's active Pokemon between turns. Or if they're desperate, they'll use up any Max Potions, Pokemon Center Ladys, escape ropes/switches, or energy to pay retreat costs to stop the poisoning before KO.
Hope that helps!