Palkia would win.1. Roar of time has 150 power and is super effective, while spacial rend only has 100.
1. Spacial Rend is much stronger than Roar of Time.
2. Palkia can learn certain ice moves, which would pound Dialga to dust.
3. Palkia is pink! (o3o lol wut?)
4. Palkia can create and destroy dimensions.
5. Awesome cry.