Solar Power

 is a Pokémon ability introduced in the fourth generation. It increases special attack at the cost of health.

Description
During harsh sunlight, Solar Power increases the Pokémon's Special Attack by 1.5 times, but the Pokémon loses 1/8 of its maximum HP at the end of each turn.

Pokémon with Ability

 * Sunkern
 * Sunflora
 * Mega Houndoom
 * Tropius

As a Hidden Ability

 * Charmander
 * Charmeleon
 * Charizard
 * Helioptile
 * Heliolisk

Trivia

 * Chlorophyll, Dry Skin, Forecast, and Flower Gift are other abilities affected by harsh sunlight