The Dallas rapper has retained the services of attorney Daryl K. Washington, who says his client is being falsely accused and everything he's being alleged against him of is without merit.

FWIW ... YB's being accused of a lot, along with Chris and a few of his homies on the night of July 20, following the kickback of the R&B megastar's 2nd concert at the Dickies Arena.

We broke the story ... a security guard, along with 4 other men, claim they all suffered gruesome injuries after Chris Brown ordered Beezy and the crew to physically assault them over an alleged clash in the past.

"Based on the information that we know, the lawsuit that includes Markies Conway, or Yella Beezy, is frivolous and without merit..." Washington says in a statement via his Washington Law Firm P.C.

"[Yella Beezy] was not involved in any incident, did not have any contact with the Plaintiffs, and does not understand why he is named party in the lawsuit or the temporary restraining order that was clearly filed before all facts were obtained and verified."

According the lawsuit, the Plaintiffs were escorted backstage along with 40 women where everyone's phones were confiscated for privacy ... which probably explains why no footage -- good or bad -- has surfaced since the filing.

Beezy posted several pics of him and Chris backstage at the Dickies arena but like his rebuttal suggests, none show any of the melee described in the suit.