Well honestly I've never been much a physical fighter to begin with, and without my magic it's hard to take a direct role. But that's okay, because the position as trainer is generally meant as strategist and tactician. These are very different from "just standing around", as you have to be actively watching the field, the opposing Pokemon, and your Pokemon, and coming up with on-the-fly tactics to counteract what the other side is doing or what you think they're about to do, while doing your best to set things up for your side.