I got selected as a primary teacher in the central government but I forgot to mention a case filed against me in 2009 under sections 323/324/34 IPC 506. The case was dismissed after trial in 2015. Will this create any problem in getting the job?

Under Indian law, a dismissed case is generally not considered a bar to employment. However, the government may conduct a background check which might reveal this information. You should disclose this information to the authorities at the earliest opportunity and provide details of the case dismissal.