I'd go out of my way to make us lose once I'd finished the event for myself. Please don't add this as a feature. The Raids/Carnivals are fine. (Perhaps add Tag Duels with a friend Vs the AI.)
I'd blame my incompetent partner for losing half the times cause they misplay or are just playing a bad deck (which does happen often). So the tag system wouldn't be a great idea unless like a friend feature was added
*sigh* I meant a way to invite friends, start up a group in tag duels, or a password system, ya know like ygopro? I wasn't just talking about a friend list :/