"We're thrilled to add a player and person of Shaquille's quality to our roster," said Steve Kerr, Suns president of basketball operations and general manager. "We believe this addition strengthens our team."
Though All-Stars Steve Nash and Amare Stoudemire have the up-tempo Suns atop the Western Conference, they couldn't pass up an opportunity to pick up O'Neal and his four NBA Championship rings in their quest to capture the elusive title.
"It's really tough to win a championship, but I really thought we had a chance to win the title the way we were," Suns head coach Mike D'Antoni said. "Things had to go right and I thought we were right on the cusp and we were doing pretty well being first in the West. But if we can better our team, then why not do it. I think we just got better."
However, with O'Neal turning 36 in March and slowed down by a sore hip that has dropped his averages down to career lows of 14.2 points and 7.8 rebounds this season, it is unclear how much gas the "Diesel" have left in his tank.
"We think he has a lot left," D'Antoni said. "He knows he's ready to roll and he will make a profound difference in our team."
O'Neal is ready to contribute, Kerr said.
"He's dying to be here. Shaquille is a winner, he's a champion. He was not happy playing for a team that is rebuilding," he said. "We feel like with our core group surrounding him, he doesn't have to be the star."
O'Neal and his massive 7-foot-1 (2.2-metre), 325-pound (147- kilogram) frame is expected to provide an inside presence at both ends of the floor even though he may slow down the Suns.
"We understand how dominating he can be," D'Antoni said. "We think we're going to get that version."
Nash endorsed the trade, even though it meant saying goodbye to long-time teammate Marion.
"It's always sad to see a teammate go, but to look back and see what has happened in the last 24 hours is incredible," the two-time league MVP said. "To get a chance to play with Shaq is pretty incredible and I'm excited about that."
A sure-shot future Hall of Famer, O'Neal was named one of the NBA's 50 Greatest Players. He owns a career scoring average of 25.6 points - ninth highest in league history - and 11.5 rebounds during his 16 celebrated seasons.
After leading the Los Angeles Lakers to three consecutive NBA titles, O'Neal, was dealt to Miami in 2004. Along with fellow superstar Dwyane Wade, the league's most dominant big man, took the Heat to its only championship in 2006.
However in just two short seasons, the Heat has declined dramatically as Wade and O'Neal battle injuries. Miami currently owns the league's worst-record at 9-38, including 19 losses in the last 20 games.
Heat coach Pat Riley was sad to say goodbye to O'Neal.
"When Shaq came to the team four years ago, I thought it would be forever," Riley said. "We're rebuilding and this is not the most desirable place to be. But Shaq's in a place where he can help the Suns win a title like he did for us."
However, Riley is excited to get Marion a four-time All-Star Marion, who owns career averages of 18.4 points and 10 rebounds while playing all nine seasons with the Suns. He is averaging 15.8 points and 9.9 rebounds this season.
Banks was the 13th pick in the 2003 NBA draft and has averaged 6.1 points, 2.2 assists and 1.6 rebounds in 289 career games while shooting 42.6 per cent from the floor in his five seasons with Boston, Minnesota and Suns.
He is averaging just five points, 0.8 rebounds and 1.2 assists as a backup to Nash.
By Paul Levine, dpa