So let me tell you a little story that happened while i was playing omega ruby.

I caught a roselia named Prince and a ralts lately named Randall somewhere nearby Rustboro city. Since my other pokemon were already leveled up to +30 for some time i mainly played with these two guys. 

Ralts wasn’t all that good in combat in the beginning, but It was a nice combo for gaining exp and they leveled up pretty fast together. But then ralts turned into kirlia and they switched places. 

And then, well, i found a dawn stone on the Victory Road. So now i have a giant baby gallade and a smol roselia.