During a bitter Democratic primary, Mr Biden was heavily attacked by critics like Mr Buttigieg and vice president-elect Kamala Harris who have since found a home in the next White House.
While Mr Buttigieg and Mr Biden called each other “no Obama” as they battled to compare their records to the last president, the tussle was mild compared to accusations around race and gender levelled by Ms Harris before she joined the 2020 ticket.
“I hear vice president Biden saying that this is no time to take a risk on someone new,” Mr Buttigieg said at a town hall in Decorah during the Democratic primary.
“But history has shown us that the biggest risk we could take with a very important election coming up, is to look to the same Washington playbook and recycle the same arguments and expect that to work against a president like Donald Trump, who is new in kind.”
The Biden campaign launched negative attack ads during the primary that said Mayor Pete was installing decorative lights under park bridges while the former vice president was helping pass the Affordable Care Act.
“Under threat of a nuclear Iran, Joe Biden helped to negotiate the Iran deal, and under the threat of disappearing pets, Buttigieg negotiated lighter licensing regulations on pet chip scanners,” the narrator said.
On the campaign trail in February, Mr Biden said the Democratic party was at risk if it nominated someone who has never held an office higher than mayor of South Bend.
“This guy’s not a Barack Obama,” he told reporters.
On that, at least, Mr Buttigieg agreed.
“Well, he’s right; I’m not. And neither is he,” Mr Buttigieg said on CNN’s State of the Union. “Neither is any of us running for president. And this isn’t 2008; it’s 2020.”
Mr Buttigieg’s attacks on Mr Biden as a risk to their election chances were ultimately proven wrong as results showed the former VP to be a more popular nominee than Mr Obama in 2008 or any president in the history of the United States.
While Mr Buttigieg’s criticisms were answered by Mr Biden’s victory, the accusations levelled by Ms Harris remain hanging.
Ms Harris said she believed women who accused Mr Biden of making them feel uncomfortable with “demeaning and disrespectful” inappropriate touching or kissing.
“I believe them and I respect them being able to tell their story and having the courage to do it,” Ms Harris said at a campaign event in Nevada.
She also said Tara Reade, who accused Mr Biden of sexual assault while he was a US senator, “has a right to tell her story”.
During the first Democratic primary debate, Ms Harris famously attacked Mr Biden for working with people who built their careers on segregation of race in the US to oppose the bussing of minority students to better school districts.
“There was a little girl in California who was part of the second class to integrate her public schools and she was bused to school every day. That little girl was me,” she said.
When asked how she went from being a passionate opponent on bedrock principles to becoming Mr Biden’s running mate, she dismissed the questions as a “distraction” and laughed it off as a debate.
“You landed haymakers on Joe Biden, I mean his teeth were like chicklets all over the stage,” said Late Show host Stephen Colbert. “Not everyone landed punches like you did.”
“It was a debate,” Ms Harris repeated, laughing.
“So you didn’t mean it?” Mr Colbert asked again.
“It was a debate,” she laughed again.
“The whole reason, literally it was a debate, it was called a debate, everyone travelled to the debate, there were journalists there covering the debate, where there would be a debate of differences of opinion and issues,” she again laughed, leaving the question unresolved.