This is the modern standard. If you use the Pokefirered decompilation project (which turns the ROM into readable C code), Porymap is a dynamic tileset editor that allows unlimited tileset sizes and real-time palette editing. It has largely replaced the old binary hacking tools.
: This is currently the most recommended "all-in-one" binary hacking tool. It features a built-in map editor that allows you to: Expand Map Size : Easily increase map dimensions by clicking side arrows. Automatic Movement Permissions pokemon fire red tilesets
Place some trees (using tree tiles) around the area to create natural hiding spots for Pokémon. You could also create little water features using water tiles, which could be a home for Water-type Pokémon. This is the modern standard
: Some of the most sought-after custom sets are "DS-style" (Gen 4/5), bringing the detailed aesthetics of HeartGold/SoulSilver or Black/White into the FireRed engine. : This is currently the most recommended "all-in-one"