Full immunity was never a problem. Only Gemini got it from meteorite.
Partial immunities are those that unbalanced the game. If creatures should have more than few counters, then one partial immunity per creature is more than enough. Also not every creature needs partial immunity. Why not two? Lets look at raptors. Now they are balanced. Give them immunity to deceleration and immunity to distraction. That way they lose most counters and become a problem, especially in tournaments. With only one of those immunities, lets say immunity to distraction, they would still be easily countered.
Look at both Indos. Without immunities they would be easily countered, but with two they have only few counters. Indo g2 should keep immunity to distraction, but lose immunity to stuns, while Indo should retain immunity to stuns and lose immunity to distraction.