i cant get any tanks in thee arena part and ive killed that wierd nemisis monster and it says what u want to do i klick go back and i go to areana and the monsters ive beaten r there but no tanks
Can't really help you there, I haven't had that problem.
Try playing with invincible mode then returning to the main menu after a minute or two. That might be a glitch that I just haven't encountered in my many hours of playing that game.