Frankenstein

It is kinda tricky to make a team focused on Frankenstein with your current servants.

My suggestion would be that you make a team with Frankenstein, Irisviel and Mash in order to keep Frankenstein alive as long as possible. If you have Hans, you should start leveling him and later on switch him with Irisviel since his NP is pretty useful.

Regarding the Craft Essence for Frankenstein. Imaginary around sounds like the best option if you want to clear a wave and NP gain won't really be a problem since you have Mash(2 arts) and Irisviel/Hans(3 arts).

Lastly the debuff for Frankenstein's NP. I would suggest using the Mystic code Atlas Academy Uniform in order to remove the stun from Frankenstein. Medea will have a future strengthening in which she will gain the skill to remove an ally's debuffs.

Goodluck!

Frankenstein is like a Lancelot or Tamamo Cat : a Wave Clearer/farming unit. She is not suited for high level battles/Boss.

You need a CE that can fill her NP from the start and the only CE from the list in from the Davinci Event or His Rightful Place (Imaginary around is a +25% Quick).

You shoud use a Waver from your friend supports to fill her NP and get her all buffed up and Mash to increase her survivability.