Unless the defense team lets a few of the special forces through I'm not seeing Lu as being a real threat to three sparks in a brawl, she's going to have to rely on whatever she's done to the machinery.
Also Tarvek and Martellus are trained as smoke knights as I recall, Violetta once commented she thought Tarvek hadn't been paying attention when they had lessons together. Martellus has shown the ability to defeat smoke knights before and Tarvek has demonstrated some smoke knight tricks in the past. That said, Martellus is with the defense team not the spark team so his abilities are largely irrelevant.
Trelawney is probably a good fighter, 'Spark of the Realm' and all that.