Let's tink of the Bakugan evolving into traps in a different way. A Pokemon way. The Pokemon Eevee can evolve into many different forms, but only one of those forms. None of the others. Now, Eevee can't evolve regularly, only by a certain stone. When the stone is laced next to the Pokemon at a certian time when the Pokemon is at a certain level, it will evolve, just depending on which stone is used. See, what it evolves into just depends on certain conditions. Maybe, if a Bakugan gets to a certain G-power, or brawls against a certain Bakugan, it will evole into a trap. After all, who said all traps are ancient Bakugan? Maybe only Tripod Theta's an ancient Bakugan? Maybe the other traps are traps naturally? They just evolved from different Bakugan after haveing the right conditions? Then they evolved into traps. And the reason Tripod Theta was resurected as a trap is maybe traps are asier to resurect ancient Bakugan as instead of regular Bakugan? Note, these are simply my opinions, and I may, in fact, be wrong about this. But who knows? I may be right. We'll just have to wait for SM's official confirmation.