There is a way to test your team w/o using charisma or stamina. The idea is to have a simulation run in you brain.
Follow the procedure as given below:

>go to the WIKI site of the misson you wish to attempt. Take a note of the rarity of the units dropped as well as the level of the unit dropped.

Lets proceed with an example.
You want to attempt the 2nd misson of the current urgent misson The Treacherous Pirate. Suppose the wiki says that you can get a drop of a "silver unit of lv 20".

>Next watch any video guide of your choice from youtube (or anywhere of your choice)...While watching the video take in account of 2 things

1) The sequence in which the enemy shows up, the boss enemy(s) that show up.
2) The strongest unit of the team which is used to clear the misson.

> The 2nd point is used now. Lets suppose you find the strongest unit used to be Lv 50CC10 unit (dont bother the rarity for the time being). Then THINK 50CC10 TO BE (50+10=60) a level 60 unit.
Average this with the dropped unit's level.

(60+20)÷2=40

This mean that if your units are above this threshold you can attempt the misson and can atleast clear 1 star in it.
Also the more no of units you have in the range of lv40~60 the better you have the chance to clear it with 2~3 stars.


Now about the units you can use:

After knowing the threshold lv.
closely look at the pattern at which the enemy shows up also check the units which the player uses to stop the advancing enemy. Then setup a team which can best replace the team in the video..keeping in mind the roles (Duelist, Tank etc.) you want to give each unit during the misson.
Also keep in mind the boss that appears in the misson as well as its stats..you should have atleast 1 (better to have 2) units which can face the boss and survive few blows.
Also if ur units are weaker than the units used in the guide take an additional healer as a backup.

PS:
The method above is basically what I do before attempting any new misson.
This method is not guaranteed to work but often(~75%) works out fine with me. This value can be low or even high for others.

I know i have made some crazy assumption above..it was just to make the example simple.

Further the factor of EXPERIENCE OF THE GAME MATTERS A LOT.
Those who are playing the game for a longer duration can form teams without even worrying about the enemy😂. I target these steps for the newbie and intermediate players without offending any other similar guide or any other senior player.
Also the assumption i made about the AVERAGE TRESHOLD LEVEL...is nothing official..just my pesonal experience and calculations.

If anyone feels these steps are useful and effective plz comment back and send suggestions.

Yours Truley
Kirito Rick