An Explainer

 Trump wants documents in the D.C. case that may not exist:

In a new court filing, in which they continue to refer to Trump as President, Donald Trump’s lawyers notify Judge Tanya Chutkan they’d like to subpoena “missing” records of House Jan 6 Select Cmte

The existence of “missing” records has been emphatically denied by committee chair

Without going into the pleading proper, this explainer is actually pretty good:

NEW: Trump's team has moved to issue several pre-trial subpoenas for "missing" documents from the Jan. 6 committee. In a footnote, however, they tell Judge Chutkan that they're not positive the documents they seek aren't in the government's discovery. 1/

Instead, they tell her they have a "good faith basis" for believing they don't have them--and then fail to explain what steps they took to develop said "good faith basis." "Trust me" is rarely a good strategy with a federal judge. 2/ 

You can read the footnote here.  Basically the argument is a broad one regarding "the defendant's constitutional right to obtain and effectively use such evidence at trial."  But there is no constitutional right to a wild goose chase:

The claim of "missing" files dates back to the change in the House leadership after the 2022 midterm elections. The committee finalized its report in the last days of 2022 and before the GOP took over. They then uploaded the report, as well as all interviews, depositions, and data that they uncovered to a public website hosted by Rep. Bennie Thompson (D-MS).

But some critics have alleged that certain things are "missing," in the report.

Among the things missing that the J6 committee subpoenaed were text messages and communications among Secret Service members and others in the Department of Homeland Security – though they claimed that, due to a software update, they had no records from Jan. 5 and 6.

So this is less a delay tactic than groundwork for an appeal when this request for discovery is inevitably denied (in fact that footnote casts this motion as avoiding delays at trial).  Building reasons for a new trial, IOW.  A "throw it against the wall and see what sticks" strategy.

I'm only surprised they didn't go with Trump's oft-repeated claim that all the J6 Committee records were destroyed.