Dancing around with words, are we?
Without the light, it's quite possible that SDG would also win considering they seem to have seriously worn Ansem SoD down with that fight. Given enough time, probably they would eventually defeat him too. However, for all we know, without the light he might not have been completely annihilated... I'm a bit iffy on this.
As for the second question, if we're talking about post-HB KH1 Sora, then yes, I believe so. Sora was able to hold his ground against Xemnas when he "visited" him to sample his memories, so he might also be able to take down a few members of the Organization. Even in CoM, which took place almost immediately after the events of KH1, he was able to send Larxene and Marluxia to their demise and seriously injure Axel and Vexen. That's no mean feat, wouldn't you think?