Secret Slab, or Enigma Part.
You can't but you can find his statue which will give an item
he is in both and you might want to buy Pokemon mystery dungeon sky. unlike the other two it has the ability to recruit shaymin! also when you recruit manaphy,dialga,and palkia you can EVOLVE your starters at luminous spring and even get the item exclusive to the game SPACE GLOBE and find the ARCEUS statue at destiny tower!
if you didn't start with squirtle or don't want/know how to to evolve it, you can always find it in lake afar on the first few floors (their recruit rate is kind of low, though so bring a high lvl pokemon holding a recruit item)
Its not in the explorers of sky
i guess it's used to evolve certain pokemon with specific item
its a item that you can carry such as a friend bow which increases the chance to recruit a Pokemon once defeaten
It is a hold item that increases your recruit chances by 24%.
just like on the red versoin if u defeat a Pokemon thay MAY want to join. ther is a item that will boost the liklyhood of Pokemon joining called the friendship ribbon it is only avalible with a key or cheating>
No there is not.
It all depends on LUCK
Any random item.
Steal an item from a dungeon shop. You must be level 90 or higher and have the Golden Mask to have a good chance to recruit it. Be warned, as they are all at double speed, appear in great numbers, and are quite strong.