If the entire guitar is tuned up or down relative to standard, then you simply shift everything up or down the appropriate amount intervals.  I cover how to play all 12 diatonic major & minor scales in three main patterns in these tutorials.

https://www.guitartricks.com/tutorial/2643/

https://www.guitartricks.com/tutorial/2646/

If any one or more strings is tuned up or down a different amount than the others (drop D, open G, etc.) then you just have to adjust the patterns for that string(s).  That's more a matter of learning, practice & familiarity.

Yes, everyone should play in the same key together.

Hope that helps.