the levels of your units aren't that important,
even with all the units at lvl 50 and your vista friend captain max you have more then enough hp to stall in the first stage and take a hit from a princess turtle.
http://optc.github.io/damage/#/tran...50,58:50,394:50,20:50C1,10B0D0E0Q0L0G0R0S100H
this seems to be the fastest + safest team we have so far.
you basically use the whole team only for their specials and captain effect.
elder turtles have 200hp, don kriegs special does 0,5x his attack, so even at level one he kills a whole stage.
crocs special does 5x his attack and is your backup in case you get the secret stage. his special kills a princess turtle in 3 turns so you will probably take a hit.
princess turtles have 12500hp therefore only croc needs a few levels, his attack should be >833 (lvl 54+).
another cool thing about this team is, that it should work for all princess turtles no matter what colour