This is a sub-page of Pokémon Crystal.
All of the below trainers can be battled by enabling GameShark code 01xx43D0 01yy44D0 (where xx is the ID of the trainer's class and yy is the ID of the trainer's roster) and entering a battle with any trainer. For example, to fight Cal's first stage party, enter 010C43D0 010144D0.
(Source: Pokémon Crystal Disassembly)