Stock Indy is actually very playable.
Only an AS Indy (or anyone stupid enough to play AS Ryujo) can really stop you. Just remember that you have enough planes for 2 full waves. Even if you lose all your planes, sticking 2 attacks will already put you ahead of the AS Indy.
In T8 MM, take it slow. Generally, hold on to your main damage dealer, torp planes. Do not throw your planes into AA you know you can't survive. Use your fighters and bombers for scouting and harassing ships especially if you know they recently repaired. Once the battle flows, ships will break apart and AA modules will be damaged and you can increase your effectiveness.