Well, 1st of all... Sasuke is support / offensive stacker ninja...

- If he is P1, you need to buff him up and give him a lot of chakra (Kimono Mabui might be a good one for it, but I didnt try it yet)
- Sasuke´s immunity can be partially solved by lightning main´s 2nd passive. Since he has super armor, its more viable.
- You should use Y mystery in most cases... using that mystery every round if you have 70 chakra or above is amazing...
- His scalling with +2 Susanoo is actually pretty OP, depending on team ofc...
- His fear passive is making him a freaking amazing support as it affects immune to debuffs ninjas aswell... and it really is a deal breaker...
- His chases lowers def/res... so you can deal more damage every round...

Probably you should power up... Sasuke can be a monster with enough BP and solid team.