Wave Energy Converter (WEC) systems harness kinetic energy from ocean waves, with the power take-off (PTO) system facilitating the conversion to electrical power. To integrate the WEC system into the AC grid, a voltage-sourced converter (VSC) with grid forming (GFM) control becomes essential, especially in future grids with high penetration of renewables. A battery energy storage system (BESS) is typically coupled with the WEC system to enhance integration. BESS can be connected either on the DC side or the AC side, leading to different topologies and performance outcomes. When BESS is placed on the DC side of the WEC system (WECd) and controlled by GFM, the overall system can accurately track the reference power and provide grid support. However, if a GFM-controlled BESS is on the AC side of the WEC system (WECa), although the grid-side VSC requires reduced capacity, it may experience delays in aligning with the WEC power as compared to its reference power curve due to DC voltage variations, potentially leading to grid power imbalances. This paper presents the integration of a linear generator (LG)-based multi-axis WEC system into the AC grid, with a detailed comparison regarding the placement of BESS. A novel GFM control strategy is proposed to improve the reference power tracking accuracy of WECa system. Parameter design is explored through transfer function analysis. Simulation results show that the proposed control effectively improves the power tracking ability and controllability of the WECa system, achieving performance comparable to the WECd system.