I am confused how "Crossover Story" Achievement is supposed to work. I have Bat Billionaire next to Metal Soldierette when "Sidekicks" is buffed, but the count is not changing.
If you use someone else as your DPS, and get to an area where you aren't instant-killing anymore, then switch out your DPS to Metal Soldierette so that she can have 15 enemies attacking her, you should be able to get it.
I have had problems with it not letting me get to my destination. I tried on multiple computers and had the same problem. It says NAN.2 hours and keeps cycling, but never gets there. The distance is 0km
 "Grow Defense"){kind=icon}
 "Astral Raiders"){kind=icon}
 "Mighty Party"){kind=icon}
 "Cyclomaniacs Epic"){kind=icon}
 "Globetrotter XL"){kind=icon}
 "Crusaders of the Lost Idols"){kind=icon}
 "Barons Gate 2"){kind=icon}
 "Frontier"){kind=icon}
If you use someone else as your DPS, and get to an area where you aren't instant-killing anymore, then switch out your DPS to Metal Soldierette so that she can have 15 enemies attacking her, you should be able to get it.