1. A computer implemented method for sequential testing across multiple devices, the method comprising: analyzing test device requirements, received from a plurality of user devices, to generate automation scripts for test automation; allocating testing devices, from among the plurality of user devices, for the sequential testing based on availability of the plurality of user devices and the test device requirements; determining a sequential schedule based on at least one of a waiting time for the testing devices, a priority assigned to the testing devices or the automation scripts, intermediate data, an execution status, and a device status; executing the automation scripts based on the sequential schedule, upon identifying that an execution mode corresponding to a run mode is assigned to the testing devices, to perform the sequential testing; and obtaining, from at least one user device of the plurality of user devices, intermediate data for at least one of the testing devices, upon ascertaining a change in the execution mode of the at least one of the testing devices from the run mode to a wait mode, wherein the execution of the automation scripts for the at least one of the testing devices is dependent on the intermediate data, and wherein platform of the at least one user device being different from the platform of the at least one of the testing devices.