How is it ethical to battle with Minior?

If you know how to properly administer aftercare for a minior and if the minior itself consents, then it’s perfectly ethical. The key is ensuring proper maintenance of your minior’s shell at all times. If it sheds this shell, recall it to its ball as soon as possible until you’re capable of giving it a dust or sand bath so it can feed and build a new shell. In other words, it’s a challenge and not something I would recommend to just any trainer, but it’s absolutely possible to give a minior a happy, full life and have it battle for you at the same time.

Minior

Minior
The Meteor Pokémon
Type: Rock/Flying
Official Registration #: 774
Entry: A small, meteoroid pokémon native to the mountains where cleffa are prevalent. The most commonly sighted form is actually composed of this pokémon surrounded by a rocky shell formed from its own wastes. Minior’s true form is a ball of brightly colored plasma most commonly found in the upper atmosphere. It consumes dust at the edge of Earth’s stratosphere, and when this dust is digested, it colors minior’s plasma and forms its outside shell. When minior grows heavy enough, it falls to Earth, where its shell may break open, either on impact or whenever it’s struck by a wild opponent. The core, meanwhile, is unstable and explodes after a few seconds of exposure unless drawn into the suspension grid of a poké ball. Because of the highly volatile nature of its own body, minior often employ the move Self-Destruct in a desperate attempt to keep itself from predators. Despite the danger its very nature poses, minior is a favored companion to cleffa, who are often seen attempting to catch and ride minior in possibly the most adorable and unfortunate examples of pokémon-to-pokémon domestication in existence. It’s considered to be highly cute because of cleffa’s adorable nature and the light minior produce, but it’s considered to be highly unfortunate because cleffa don’t normally possess defenses against a close-range Self-Destruct.