>>27994921There's a book in the Platinum Galactic HQ that gives reason for using the Red Chain.
A Pokéball essentially tames a Pokémon through trust and limits its abilities to be manageable under a single trainer's care.
The Red Chain binds the spirit and forces the Pokémon to use its full potential at the will of a master.
In the anime, the Red Chain resembles Arceus' Ring.
