Xcode 2.5 Release was released on 29 Oct 2007 and requires macOS 10.4+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/xcode_2.5_developer_tools/xcode25_8m2558_developerdvd.dmg.
Release notes are located at https://download.developer.apple.com/Developer_Tools/xcode_2.5_developer_tools/relnotesxcode25.pdf.
The compilers it contains are:
- GCC 4.0 (Build 5370)