I feel your pain, Dart.
Though anyone making it to Round 3 I wouldn't necessarily call them a noob.
I think the best I got to work for me is just having my usual training partners play their secondaries and telling them to try different things. Even though they're less technical and familiar than a main, you can work on generally universal things like powershielding lasers, character specific combos, edgeguards, and dealing with their bread and butter approaches.
That at least carried me through tournaments in the past. Just playing lots of friendlies or money matches against the characters that give you a lot of trouble before the tournament will help you win when it counts, even if you're not actually good at that match-up. It's something Zhu did to M2K at Genesis1, if I recall correctly. It may even be a little underhanded, but it is an option.