Generation Iv
Solar Power
Boosts Sp. Atk, but lowers HP in sunshine.
Detailed Effect
During strong sunlight, this Pokémon has 1.5× its Special Attack but takes 1/8 of its maximum HP in damage after each turn.
Pokémon With Solar Power
10 canonical Pokémon forms can have this Ability.

Sunkern
Sunflora
Tropius
Mega Houndoom
Charmander
Charmeleon
Charizard
Helioptile 
Heliolisk
Charizard Gmax