When you battle heatran in Pokemon mystery dungeon explorers of sky he is not recruited?

That's correct! In Pokémon Mystery Dungeon: Explorers of Sky, Heatran is not recruitable. You can only battle him in the post-game story, and he is an incredibly strong opponent.

Here's why Heatran can't be recruited:

* Story Significance: Heatran's role in the post-game story is to test your strength and prove you are worthy of being a true hero.

* Gameplay Balance: Allowing players to recruit a Pokemon as powerful as Heatran would drastically unbalance the game, making it too easy to conquer later challenges.

While you can't have Heatran on your team, there are still plenty of other powerful Pokémon to recruit and use in your adventures!