Worth noting that Biden's legal team was ***massively*** prepared in the event of any post-election litigation, since they knew it was coming a mile away. They had hundreds of lawyers, and dozens if not hundreds of briefs and pleadings ready to go in the event of any scenario. This contrasts with Trump's ramshackle, cobbled-together team headed up by his personal lawyer Giuliani and the eventually-fired Powell.
https://thehill.com/homenews/campaign/516258-biden-campaign-forming-special-litigation-team-ahead-of-possible-voting
But in the end, they didn't have to do anything. The people spoke with resounding force. Not a landslide, perhaps, in the Electoral College -- but a decisive win.
So Biden didn't need to send his own lawyers to litigate these joke lawsuits and draw more attention to them than they were worth. (I'm sure Team Biden had observers in court, but they didn't need to use lawyers)
Instead they were content to sit back and watch state governments defend these joke suits, and let state and federal judges swat away these silly challenges.