The Toronto Raptors have also reportedly traded back-up centre Greg Monroe and a second-round pick to the Brooklyn Nets for cash considerations.
This season, Lowry is averaging a career-high 9.2 assists with 14.2 points and 4.4 rebounds while shooting 41 percent from the field.
The Raptors made a major move just a day after the Sixers completed a blockbuster deal for Tobias Harris.
Gasol, 34, was in his 12th season with Memphis. Prior to the trade, Valanciunas was expected to return to the Raptors' lineup against the Atlanta Hawks on Thursday night (Friday, PHL time).
"With him, just knowing his personality and who he is, I never got the sense that he didn't want to be here", Bickerstaff said. Whether he can still reach the heights of peak Gasol, a player the Raptors had eyes on over the years according to intermittent reports, is of more debate.
"I've been in rumours so many times I don't even look at it", Valanciunas said. "Mike is one heck of a player, and we're going to need good players moving forward". The Raptors (39-16) currently sit in second place in the Eastern Conference standings and are in win-now mode with no guarantee Kawhi Leonard re-signs this offseason. He's now averaging 4.7 assists per game, the highest mark of his career and the second-most among centres this season behind only Nikola Jokic.
They also lose Wright and Miles, the former a talented guy who does all the little things right but struggled to find a defined role on a deep team, and the latter a mercenary shooter who has unfortunately struggled this season to shoot.