No he's always immune even before his first action. As far as I can tell after testing him with my group mate who got him today.

I tried Shisui before he did anything and was immune.

His passives are amazing. 20% nin every round is really nice. His res&def debuff is also amazing, it works on everything that hits him, doesn't matter what or how many times you stack that debuff fast. For example Minato jonin, mystery, 1x debuff, attack. 2x debuff, 2 chases and there you go 4 stacks already, 32% gone!

as for teams, he used LM for root, Sasuke skill broke, 60% barrier is sweet, and edo hiruzen for his buff. Samui works aswell but root only hits 3 ninjas and with this lineup you have 4 sword ninja.