In Arkham Horror is it possible to exchange items during the movement phase? What are the rules? (people on same place?)
Basically, if you pass through the same location as someone else, you can give up or receive items from them. As long as it's not combat, there are no timing requirements. This is described on page 23 of the rulebook. The rules for trading items are quite generous:
Note especially that for gameplay reasons you can trade Spells, but not Allies or clues. From a thematic perspective this has always seemed a little counter-intuitive to me (You teach someone else the spell, and then... forget it? "But of course my friend can't go off with you!" "Yep, I have a clue, but I simply can't tell you about it.").