Location from pokemon-kanto by
The first major island of the Orange Archipelago — home of Professor Ivy's regional-variant research lab, where Ash delivered the GS Ball and Brock stayed behind.
Valencia is where the Orange Islands journey begins. Professor Oak entrusted Ash with delivering the GS Ball — a mysterious golden Poké Ball containing something Oak himself couldn't open — to Professor Ivy for analysis. The visit was the turning point of Brock's arc: he agreed to stay and work under Ivy, and the group continued without him picking up Tracey as a replacement. Whatever happened during Brock's tenure with Ivy remains unspecified.
A lush tropical island of palm forests, terraced citrus orchards (the 'Valencia' reference), and a coastal research compound of connected bamboo pavilions. Professor Ivy's lab sprawls at the edge of a protected reef. Regional-variant Pokémon — a strangely colored Butterfree, an oversized Rhyhorn — graze in the pens.