Note: It is easier if you have already beaten last story, it is easier if you choose challenge mode and go level by level and then do the bosses and it is preferable if you do A rank for team Rose,then Team Chaotix,then Team Sonic and then Team Dark. Get all level up for each character, don´t die, and complete the level as fast as you can. Whilst they are punching away at thin air the team blast bar is going up and up.
When you're pressing the B button the power formation leader should be punching, throwing or whatever that chosen person's attack are like. To fill up the team blast bar without killing any enemies or collecting any rings, just switch to power formation during any level with any team and press the B button repeatedly until the bar goes to maximum. You should end up with metal charecters on the team you used the cheat with. When its loading hold the A+Y buttons down and don't stop holding them until the entire loading process has finished. Once you have done that the origonal 1990's loadin screen will come up whilst it loads the level. To get metal charecters in the multiplayer matches simply choose the event as usual then you'll need to pick the teams.