The Copies Have Been Learning on Their Own: Madrox and his Madrox Dupes can use the standard attack and damage powers that opposing characters adjacent to them can use. (They lose the power as soon as the opposing character is no longer adjacent.)

If a dupe is next to a character with say prob, but Madrox himself is not, can Madrox use prob?

The way I would rule it would be "no" but i'm not a judge (hence why I'm here).

I feel like it's slightly ambiguous (or enough to where I can see someone questioning it).

No. Madrox himself would need to be adjacent to the opposing character to use Probability Control. They dupe can use Prob though.

Both his dupes and him could use said Probability Control, but any piece (Dupe or pile) would also need to be next to the figure that has said Probability Control.

This is how it reads to me.

I have to lean in this direction. It could say:
or
or some other variations, but as is, it's less restrictive. This could use a clarification though.

Agreed. The "Madrox and his Madrox Dupes... characters adjacent to them can use" is the part that speaks to me. Both characters (either/or) can use the power when an opposing character is adjacent to them with the power.

I read it as each individual character only being able to use whatever powers that the opposing characters adjacent to those particular figures can use.

Madrox is adjacent to someone with perplex? He can use perplex.
Duplicate #1 is adjacent to someone with shape change? Duplicate #1 can use shape change.
Duplicate #2 is adjacent to someone with pulse wave and outwit? Duplicate #2 can use pulse wave and outwit.

It isn't a universal application where they can all use perplex, shape change, pulse wave, and outwit.

I think that it might be worth an official question on the Wizkids forum, though.

This is correct. Each of these characters (Madrox and his Dupes) are checking for adjacency and powers individually. They do not further grant use of those powers to each other.