If it's a stock replacement it shouldn't need to be tuned. If it's a built trans or an upgraded trans and you're replacing or upgrading the torque converter with it, you're going to want to dial it in correctly on the tune.
Things that can be tuned for trans/converter:
Shift Point Tuning
Full throttle shift speed
Full trottle RPM
Half Throttle Speed
Half Throttle RPM
Torque Converter Clutch Duty Cycle (max/min pressures)
Torque Converter Clutch Apply/Release speed (aka lock up)
Also, Always a good idea to do the rear main seal when the trans is out like the trans guy said.
2006 GTO M6
Motor - Stock with Vararam
Bunch of suspension
Bunch of brakes
12.81 @ 110.6 2.03 60'