ok here is how you should do this
using shinx and changing the tatics on cynda move behind dialga and attack with your own regular attacks then change the Iq terms to your person to exclusive move user and set the only move you use to flame thrower and after flame thrower runs out spam rollout I think that lava plume hits all pokemon in the room or close to you so change tatics on cynda to go fight enemies or something if lava plume only hits close range pokemon and eventually dialga will fall. If shinx has a long distance attack or gravel rock or a spike stick or watever use those as well
