Of course, when you beat Raquaza in Story Mode, a gap will be opened, unlocking Luminous Cave, only one poke'mopn can go in at a time, but when you evolve, your stats will raise, but certian requirments may be needed. If you don't want to evolve, but you want someone else on your team to evolve, you go to their freind area, select 'Join Team', then select 'Make Leader', then go to your freind area, and select 'Stand by'. Then, go to Luminous Cave alone, then you may be able to evolve. I got Sqirtal, my main partner, to evolve into a Wartortal. It's a long process, but it's sweeeeeeeet!