Beating Giovanni

The Viridian Gym Leader is Giovanni, the boss of Team Rocket - the same man you beat in the Rocket Hideout and again in Silph Co. This is the third and final round, and the gym only opens once you hold seven badges.

Step 1: Bench Pikachu

Electric does nothing to Dugtrio, Nidoqueen, Nidoking or Rhydon. Your partner has no business in this fight.

Step 2: Lead with Lapras

Surf plus Ice Beam covers his whole team. Rhydon is Ground/Rock: it takes 4x from Water and 4x from Grass.

Step 3: Grass is the other answer

A Venusaur with Razor Leaf (high crit rate in Gen 1) tears through Rhydon and Nidoking.

Step 4: Respect Dugtrio

It has 120 base Speed, which in Gen 1 also means a permanently high crit rate. It will move first and it will crit.

Step 5: Fight

Reward: Earth Badge and TM27 Fissure. Team Rocket disbands on the spot.