Put bike on centerstand. Grab swingarm near the end and try to move swingarm from side-to-side. Any movement = bad bushings.
Spin the rear wheel. Sound like a box of rocks? Bad bearings.
Grab opposing sides of rear wheel and try to twist wheel relative to swingarm. Any movement = bad bearings.
Testing shocks requires shock disassembly of the shock. If they're the stockers, replace them.
mystic_1