I don't know about everyone else, but on Generations you need loads of lives to do runs with skills. I know you can die and get a gameover to restart, but that takes up time that people don't want to use. And it's pretty hard to die against shadow - he has to get both his powercores to kill you.
So what are the best techniques for getting alot of lives fast (don't mention buying them from omochao's shop because that's kinda obvious).