Have a lot of interesting boss npc, but they lack jutsu to up the difficulty of there difficult other then hp and a shuriken throw and some with other extension beside hashirama. Here some ideas
Kabuto: snake summoning that attack the player or chase, basically white snake critters. Summon after half no come sets with 20k health and causes poison upon hit.
Sasuke: chidori and nagashi 4x4 aoe trigger when close like hashirama spikes, the chidori increases sasuke speed and makes him homing on you after 5seconds then returns back to normal.
Orchimaru: summon a sword that extend 4title in front of him, upon hit causes bleed. Remove rogues and replace with mini attacking snakes poison ailment up on hit.
Mu: summon a particle cube at low hp in front if you an ohko but can shunshin out of it to avoid it takes 3seconds to land. Summon a clone that disappear after 30seconds.
Kisame: water shark projectile that explode and do a 3x3 basically his clan technique in the game, and water prison for 1tile in front of user.
Dark indigo: slash 2tile away from user, flame coat, attempt to land tai causes burn ailment, fire dragon jutsu, throw a 1tile Dragon explode upon contact.
Copyist bj: poison gas 3x3, poison cloat, and poison needle throw increase to a 3 time throw instead of one.
Sage Rico: Earth cloak, reduces damage, an throw that increases the shuriken throw basically weightless, and a 3x3 aoe that summons a jiriaya like swamp and slows the opponent for a clean jerro sembon and or attack.
Kabuto: snake summoning that attack the player or chase, basically white snake critters. Summon after half no come sets with 20k health and causes poison upon hit.
Sasuke: chidori and nagashi 4x4 aoe trigger when close like hashirama spikes, the chidori increases sasuke speed and makes him homing on you after 5seconds then returns back to normal.
Orchimaru: summon a sword that extend 4title in front of him, upon hit causes bleed. Remove rogues and replace with mini attacking snakes poison ailment up on hit.
Mu: summon a particle cube at low hp in front if you an ohko but can shunshin out of it to avoid it takes 3seconds to land. Summon a clone that disappear after 30seconds.
Kisame: water shark projectile that explode and do a 3x3 basically his clan technique in the game, and water prison for 1tile in front of user.
Dark indigo: slash 2tile away from user, flame coat, attempt to land tai causes burn ailment, fire dragon jutsu, throw a 1tile Dragon explode upon contact.
Copyist bj: poison gas 3x3, poison cloat, and poison needle throw increase to a 3 time throw instead of one.
Sage Rico: Earth cloak, reduces damage, an throw that increases the shuriken throw basically weightless, and a 3x3 aoe that summons a jiriaya like swamp and slows the opponent for a clean jerro sembon and or attack.