Simplify the following text for a Grade 6 native English-speaking person.
Original: PokÃ mon entered its third generation with the 2003 release of PokÃ mon Ruby and Sapphire for Game Boy Advance and continued with the Game Boy Advance remakes of PokÃ mon Red and Green , PokÃ mon FireRed and LeafGreen , and an enhanced remake of PokÃ mon Ruby and Sapphire titled PokÃ mon Emerald .
Simplified: In 2003 , PokÃ mon Ruby and Sapphire were released . They were the first PokÃ mon games on the Game Boy Advance , and this upset many players because they could not trade PokÃ mon with Red , Blue , Yellow , Gold , Silver , or Crystal .