Except for the feuding County Council--have agreed to run for reelection as a slate, prompting complaints of "foul" from at least three challengers, who accuse them of fostering bossism in a county that has a tradition of good government.

Formation of "Democrats For '82" had been opposed by some of the incumbents, including State's Attorney Andrew L. Sonner, who two months ago called the idea "undemocratic."

Pat Billings, the campaign coordinator for the slate, said, "We are not discouraging anyone from running. I don't think it's our intention to shut anybody else out."

The slate, which has a campaign office on Rockville Pike, plans to raise $50,000 and mail 120,000 sample ballots to county homes. Retiring State Sen. Victor L. Crawford will direct the joint campaign.

The ticket will include Gov. Harry Hughes, County Executive Charles W. Gilchrist, candidates for the legislature, four incumbent circuit court judges (who also will run in the Republican primary) courthouse officials and central committee members. With the deadline for filing Tuesday, all but Recorder Rosalie Reilly and some of the legislative and central committee candidates are facing primary opposition.

Wade Dunn, a Rockville businessman who is challenging Gilchrist, called forming a slate "irresponsible. I think it closes out what democracy is all about. I think it smacks of machine politics and I don't think the majority of Montgomery County voters will approve of that process."

Rockville lawyer Daniel Cassidy, waging his second primary challenge against Sonner, recalled the prosecutor's earlier criticism of slate-making. "I think Sonner's too weak to run on his record," Cassidy said. "It just shows that he's a slippery politician and not a law-enforcement official."

Sonner repeated yesterday that "I do not approve of it. I do not think it is in the public interest." He said he agreed to be included on the slate because "I don't want to be a problem for my other teammates," but said he will not contribute to it.

Lawyer Abbe D. Lowell, who said he has raised $25,000 in his race for a 16th District legislative seat, said "this will make them the party of slates and backroom deals."

Del. Judith Toth, who like Sonner had initially criticized the idea, said she would run alone rather than pay the $1,000 fee asked of delegate candidates. But Sen. Laurence Levitan and Del. Jerry Hyatt from Toth's Potomac district agreed to pay her fee, rather than risk division. "It's kind of coercion," Toth said. " . . . . But if the boys are willing to pay it--and they say they are--then I say fine."