The Ranger infront of Rentlebud Cave lets you pass so you can... *Read Ash493's Post*
Latios, just like Normal Ruby, is flying around GENTO after beating the elite four.
In Reign of Legends? Land south from Mt.Pyre and talk to the lady near the berry trees.
*These 'random coulored spirak thingys' leads you to rocks that gives you four keys.
N.B.: I'm not sure but the puzzles of fate gives you keys too, so I don't know if you can choose one of the two, I gave up with Rescue Rangers, became so hard...
*And you have to fight them because you made a different future, and to prevent two futures from happening, they must kill Jagold 'Fortunately they didn't kill him, for it has happened, I couldn't play Life of Guardians :P, but Breatherna had to suffer two futures. Ha! Actually, I'm feeling sad. Breatherna's my favorite Guardian...'
I believe Breatherna's a female?