Ender is able to take care of himself. Indeed, Ender doesn't really know just how capable he is until a situation presents itself. Consider when Bonzo and a group of his boy thugs corner Ender in the shower. Ender uses his skills of manipulation to force a one on one confrontation (Spanish honour). Ender ends up smashing Bonzo's nose into his brain, killing him. Ender is horrified what he is capable of. Still this tells us that unlike other boys, Ender has the personal resources to do what he needs to do. Ender's army destroys pretty much everybody els's army in simulations. Ender is able to think on his feet and even improvise on the spot.