Alright, Like all sites we too have a Limited and ban list... NOT we prefer not to ban those things every cannon jutsu is allowed but it would just have to be modified to be less OP limelight for example wont be able to auto hit
also user's with rinnegan must either create a custom path or one of the canon ones, the canon rinne tech is the only things limited. For one user with rinnegan
Deva Path. (0/1)
Asura Path. (0/1)
Human Path. (0/1)
Animal Path. (0/1)
Preta Path. (0/1)
Naraka Path. (0/1)
Now for the limited to start with,
Rinnegan (1/2)
Mangekyuo Sharingan (0/5)
Eternal Mangekyuo Sharingan (0/4)
Impure World Restriction (0/5)
All the limited above can be taught by someone who knows it. There is no limit to anything except for the canon paths in character.