What fast move A Zapdos use is not sure, but it looks Peck. Electabuzz's fast move is also not exactly sure but it maybe Low Sweep.
The defender uses Thunder, an electric-type charge move, and the move is super effective against Zapdos.
The Zapdos defeats the Electabuzz but is fatally wounded.
Zapdos vs Vaporen
Vaporen's fast move seems to be Water Gun, but it is not very effective against the Zapdos. Zapdos' fast move is also not effective against the second defender but the reason is not sure. If the move is Peck, it should not be not very effective against the water-type Pokemon.
Even though Zapdos is electric- and flying-type Pokemon, it uses Hydro Pump, a water-type charge move. It is weird. Finally, the Vaporen defeats the legendary bird by Water Gun.