A good fighter has a decent barrier of entry for newbs but has a scalable level of difficulty for longtime fans. Open juggles help so they can be creative with their combos. For newbs Capcom perfected rush combos so if you have a gauge, you can pull off combos they would never normally be able to naturally string together. Its really about balance, the personality of your characters and the interaction with the levels. The reversals need to be fluid. It also depends on whether its 2D or 3D so you might need to be specific because they play differently.