This is another outside the box idea but taking everything into consideration in this post. What if we take all three of these teams and move different pieces. I'm looking at this as the Pelicans are wanting to get off Zion's contract and the Blazers are wanting Jaylen Brown.
Celtics Trade - Jaylen Brown and the 35th pick (Blazers)
Celtics Trade - Malcolm Brogdon, S&T Grant Williams, Payton Prichard and Celtics 2025 1st (Pelicans)
Blazers Trade - #3 1st Round, Anfernee Simmons, Shaedon Sharpe (Celtics)
Pelicans Trade - Zion Williams (Celtics)
Celtics take a chance on Zion who's value is dropping, who is a different player then Brown. They receive a scoring shooting guard in Simmons and Sharpe being a SF/SG combo, and being able to draft Scoot Henderson. Blazers get Brown to pair with Lillard. Yes, they're giving up a lot but it will depend on what Lillard wants. Even if they want to keep Sharpe I'd still do the trade but I'd push for him. Pelicans get rid of Zion's contract, receive a starting point guard, moves McCollum to the shooting guard, Ingram to the small. The receive a starting power forward for a lot less in Grant who can space floor, a backup in Pritchard and a future first.
Celtics starting 5
C - Williams
PF - Zion
SF - Tatum
SG - Simmons
PG - Smart
Backup 5
C - Horford
PF - Hauser
SF - Sharpe
SG - White
PG - Henderson