Creating a destructive EMP typically requires discharging a high voltage capacitor or a high voltage energy-storing delay line into a radiating load (an antenna) using a very fast switch. The faster the turn-on, the more high-frequency content in the radiated EMP. Pulse widths of a few microseconds and turn-on times of a few picoseconds with pulse repetition rates upwards of a few kilohertz are possible. The voltage required to generate a significant (destructive) amount of EMP energy is upwards of ten kilovolts. Stray inductance and stray capacitance and circuit resistance are not your friends as these must all be minimized. I wouldn't even consider using this technology, which is very sophisticated, as a weapon in a robot fight. It might work once, but then the opponent robot would simply "shield up" against the EMP for the next contest. Have you considered "brute force" (bigger, heavier, more power) to overwhelm the opposing robot?