Inverter-based generators (IBGs) are becoming popular in modern power systems. When the penetration of IBGs is increasing in power systems, new stability, protection, and monitoring challenges are introduced in the grid. Grid-forming (GFM) control of converters is seen as a promising solution for future power grids to overcome particular stability challenges. Here, the technical challenges of the GFM-based IBGs are reviewed from the point of view of TSOs and academic research. The properties of different GFM methods are studied for different GFM-based IBGs for a single grid-tied IBG and using the IEEE 9-bus test system. Simulation results are provided by using the PSCAD-EMT simulation software.