There is a lot to think of, I messaged
@ZeroGravity to clarify, so that's the only reason I knew a bit more.
I'll let him answer to it since I'm pretty out of place to answer, but from what I gathered he wanted a very easy-to-use system for a game in which it seemed each player would only have one Hero that would be relevant to trading.
I had a plan, but they had a lot of overtime available at work so I haven't started yet although I told him I would if no one took interest before it was convenient to me.
From talking to ZeroGravity, my plan was to make a system which
1. Assumed each player had one hero.
2. When one player initiates a trade proposal by naming the player they would trade with like so "-blue" for player 2 et c.
3. The offered player would be presented the details of the trade (something like "SomePerson wants to trade their Level X Blademaster for your Level Y Archmage" (if in a dialogue then do agree/disagree buttons, if text then continue the message with "Type '-yes' to confirm or '-no' to deny this trade."
I didn't get far enough to ask whether there was any preference of Dialogue vs displayed text.
To me, this seemed like it could be blown up into a simple system that others might use so I was thinking I would make something a little more dynamic and then I would reduce the commands/functionality to ZeroGravity's needs since that's more than was asked for and I didn't want to over complicate the system requested.
Alright, I'm butting out now lol