In my front 3 Yokai I have one with the Popularity skill, which makes befriending easier. However, in the back I have one with Unpopular, which does pretty much the opposite. Do their skills cancel each other out? Or are skills only "active" for the front 3 Yokai?
Popularity and Unpopularity are in effect when the Yo-kai with them is alive, regardless of if they are in the front or back. When any battle starts, the top screen will show a message stating that certain Skills are in effect, both of enemies and of allies. For Skills that only work when in a specific position, this message will state the position required for the Skill to apply instead of that it is in effect. Most Skills don't have a message. Those Skills only work for the Yo-kai with them, and as such don't work while the Yo-kai is in the back, because their condition can't be triggered (the game won't pay attention to the rotation of the wheel until the next Yo-kai takes an action, as such Wobblewok's second attack acts as though the wheel wasn't moved if you rotate it during the first and it gets a second attack).