He did have Stonewall Jackson prior to Gettysburg. Had he fronted Little Round Top early on July 2nd, the CSA likely wins the battle.
Lee should have fought strictly small hit and run engagements, throughout the war. He was constantly outnumbered and lacking artillery, to effectively compete against the Union Army. What he accomplished early in the war, is amazing considering these disadvantages.
Had Lee stuck with gorilla tactics, as Jackson did during his successful Valley campaigns, Lee would have prolonged the war and saved his outnumbered army. This might have resulted in a peace agreement or assistance from the UK.