Filled with a continuous rage, the feeble mind of a Slowbro was suppressed by the vigour of Electrode. As such, it continually bursts out in a fit of electrical rage because it has no urge to move, while simultaneously having a need to fight.
If the Shellder on Electrbro's tail draws too much electricity, the Pokémon becomes unstable and may erupt violently. It is said that the Shellder's poison helps regulate this energy, preventing a total detonation.