Not a big fan of trading for Beal, but I'll play along.
(click on image to enlarge)

Add as many pick(s) as you see fit. The Knicks may be willing to throw in a pick as well.
I guess we'd take back at least one more contract from the Wiz otherwise they'd have to cut 2 players.
C's roster after the trade
PG: Smart - Pritchard - Teague
SG: Beal - Green - Edwards
SF: Brown - Semi -
PF: Tatum - Grant -
C: Theis - Thompson - Timelord
Wizards starting lineup after the trade
PG: Westbrook
SG: Romeo / Nesmith
SF: Avdija
PF: Hachimura
C: Randle
For the record, I fully believe the Wiz can get better value for Beal. But then again, maybe that's just me cause I'm low on Randle.