I was wondering, since Duo attack is no longer a thing. When it comes to equipping a character, it has to be a "standard character"

Standard character
• Isn’t a bystander
• Has a single base or peanut-base
• Has ;Fist; as its only attack symbol, has ;Shield; or ;Indomitable; (or both) as its only defense symbol(s), and has ;Standard; as its damage symbol.

However someone asked if ;Sharpshooter; counted and it was ruled yes, it counts. So does duo also count?

I would not count it

No, duo was never considered "standard" but sharpshooter was from early on.

I've still been playing Duo Attack...am I wrong?

No. At my venue you can definitely play duo. You just can’t equip them.

Duo attack is fine, I was just wondering if makes them a Standard character or not, your fine!

No powers or effects have been removed from the game with this rule update... some things have been retired (including duo attack, ultra heavy/ light objects, etc), but like all other "old rules", they work the same as they did with their last iteration of rules (or as close as they can with modern language).

Speaking of Duo Attack - does the second attack still have a -1 to damage? Or was that only due to the defunct "Damage Depletion Modifier?"

Damage Depletion Modifier is no longer a thing in modern age with the exception of Team Bases those are still required to use it

One, there are no team bases in Modern. Two, there is no DDM, for anything, period. It's no longer in the rules at all, so it can't possibly apply to team bases, or anything else.

WK's at one point said the intention was to re-implement the idea for things like team bases, but it never actually happened. There were several other changes brought up during the rules transitions that were later dropped/changed/whatever. Bottom line, it was never implemented in any official capacity, and since they refuse to address non-Modern game elements, and have seemingly just completely given up on the proposed "Past Rules Document" (it's been over 2 years now), it doesn't matter.

The -1 atk was originally baked into Duo Attack. Later on, as they introduced more game mechanics that allowed for multiple attacks (specifically team bases), the modifier was removed from Duo Attack and the DDM was introduced.

The last version of Duo Attack that existed didn't have the modifier, and that's the version we still use.

To address the original question, no, the Duo Symbol would not be considered standard.

Sharpshooter was considered standard before it was retired. Duo was not. The Sharpshooter ruling just reinforces the stated intention of keeping retired elements functionally the same as much as possible.