ditto CP (another ditto question...)

I've caught four now and not spotted a relationship. The only thing I've noticed is the Ditto CP/Lvl influences how easy they are to catch.

It seems to me that a transformed Ditto will have the same CP as if it were the actual Pokémon. So a level 20 Ditto that is transformed into a Pidgey will have the same CP as a level 20 Pidgey (IVs excluded ofc.). This also happens in a gym - fighting a level 30 Ditto with a Dragonite will turn the level 30 Ditto into a level 30 Dragonite in terms on CP. So yes, low cp transform = low level Ditto.

I caught three Dittos with very low, middle and high levels, it seems before catching they show the CP of the mon they mimic (I had three different ones, a Rattata, a Zubat and a Magikarp)

One thing about ditto that I think people forget about is that due to its low Hp (mine has 58 at level 17) its a very effective attacker if your looking to conserve potions. If you fight a Snoralax for example and switch out ditto before fainting you can put in 2 potions and reuse it again. Not sure a 3K drgaonite is even that efficient.