My style?..... Brazilian Jiu Jitsu/Judo/Sambo hybrid..... My struggle? Not killing people daily who ask me to teach them rolling knee bars when they can't even catch a basic armbar from the mount when their opponents arms are straight up
Seriously though, I play multiple positions, when I'm playing off my back, I prefer close guard with an overhook, or an assortment of open guard setups and attacks (butterfly, spider, lasso, half, DLR, X, Single leg X)... Top position I like to smash the guard and play side control/knee on belly attacks, or in no gi attack leg locks. I also love back attacks..... From stand up I prefer Judo and Sambo takedowns, I'm not so much a shoot wrestler anymore, but I do love single legs.
When it comes to struggles, guard passing (especially against other black belts with high level guards) is always a grind.