There are many types of weapons you can outfit your robot with. Here they are, arranged in order of simplicity.
BMW (no weapon)
BMW stands for Battery, Motor, Wheels. A BMW type robot is just that. They are usually big, bulky, and strong, since no weight is wasted on weapons. They may have spikes and spears to help subdue the opponent. Robots without active weaponry are classified as BMWs. They are usually boring and not crowd-pleasing.
Thwack-bots
Thwack-bots use kinetic energy stored from the vehicle�s rotation to inflict damage. They are usually in the form of a box (where the motors, batteries and wheels are located) with a strong, hammer-like tail. The robot spins around, and tries to hit the opponent as many times using their weapon. Thwack-bots are generally hard to steer, but simple to make.
Chameleon Robots
Chameleons have detachable/modular parts that can be customized depending on the opponent. For example: When fighting a spinner, you can attach a thwack-bot type appendage, so you don�t need to get too close to the spinning robot body. When fighting a KE or blade robot, more armor can be added on demand. When fighting BMWs, you can attach a hardened metal spike to attack the opponent�s armor and/or wheels. When fighting a lifter, you can add low-clearance armor skirts to avoid allowing the lifter to get underneath. These are complicated to design, but effective.
Cutting Blade Robots
A robot can be armed with a cutting blade or shears to try and break through the opponent�s armor and damage their internal workings. These weapons usually inflict minimal damage, but the audience loves them. Especially when a carbide-tipped saw blade attempts to grind tool steel, creating a shower of bright sparks. Even if they don�t win, they�re always popular.
Kinetic Energy Weapons
A robot with a kinetic energy weapon, such as a rotating hammer or flywheel inflicts damage by transferring that stored energy into the opponent. Remember that the robot itself needs to be strong enough to withstand the shocks involved, since each action has an equal and opposite reactions. These robots are generally slow to maneuver, since most of the weight is invested in their spinning weapon.
Spinner
Spinners are essentially robots equipped with a K-E weapon, but the weapon encloses the whole robot, such as a rotating shell with hammers. Again, these are even slower because lots of weight is devoted to the weapon-drive motors. They prove to be the hardest to attack, because it is defended from all sides by its weapon.
Lifters
Lifters are one of the most successful and exciting types of robots. It has an arm that is powered by an electric motor or operated via pneumatics that is designed to get under the opponent�s robot and flip them over. Very few robots are designed well enough to withstand being flipped more than once or twice.