I will have plenty to give you tomorrow, which is probably when I will post a new beta I will need you to edit for me in some scripts.
For now, think you can adapt the titlescreen (its an Emerald ROM, don't forget) to show Mew and, perhaps, a temple? Temple in the sense, for example, stairsways to a chamber. Something that can illustrate a temple. It doesn't take many colors, so it'll be all we need for now. Got the needed sprites for the job?