I don't have my books with me right now as I am in the middle of a move. But I am working on a campaign plot line that would involve a dragon. AIR some dragons had shapechange, however, I can't remember if that is true in 5E or not or what dragons have the ability. Could someone point me to the answer in the compendium? I am not seeing Shapechange as a feature of any dragon I look up. 

Thanks

All the metallic dragons from CR 15 up have the Change shape feature. (example: Adult Bronze Dragon)

Well I guess I can change the alignment to keep things interesting. Since all the metallic dragons are good alignments. 

Remember the stat blocks are average. Every dragon (and all other monsters) are individuals with the ability to make decisions. Just because most metallic dragons are good doesn’t mean all of them are. As a supplement remember the most memorable villains are the ones who feel they are doing the right thing. 

As above, you can always give any individual dragon the Change Shape ability - a particular blue dragon in Storm King's Thunder also has it. The key is that the ability is very particular about what it allows the dragon to transform into.

Also, there's always the dragon's Innate Spellcasting feature. Though they don't normally have it in order to cut down on DM accounting, any dragon can have spellcasting, which you could use to (for example) allow it to cast Alter Self for any medium form instead of the usual. Shapechanging is an old trick for dragons, so I think it's well within expectations to give them ways to do it.

A dragon who hasn’t ever looked at a spell book is a) really young b) really lazy or c) not smart enough to see the advantages of being able to literally warp the fundamental laws of the universe.