Quoted By:
Light-type
Super effective against Ghost (shadows), Water (purely for balance), Fairy
Not very effective against Ice and Rock (refracts light)
Does not affect Grass (photosynthesis)
Resists Ghost, Fairy and Light
Weak to Bug (bugs are attracted to light), Grass and Electric (something about waves and particles i don't remember from high school physics). Excluded Fire-types with flames because that's a cop out option
Retyped moves: Moonblast, Aurora Beam, Signal Beam, Solarbeam, Psybeam, Wish, Light Screen, Reflect, Flash, Tail Glow, Mist Ball, Luster Purge, Mirror Shot, etc
Retyped mons:
Chinchou (Water/Light), Mareep (Pure Light), Starmie (Water/Light), Volbeat (Bug/Light), Luxray (Electric/Light), Heliolisk (Light/Electric)
>but muh psychic-type
Psychic moves remain based on telepathy, telekinesis. Move/Pokemon based on illusions or invisibility can go either way
>But muh fighting-types
Still based on martial arts and chi moves, completely unaffected
>but muh fairies
They remain a clusterfuck. If they don't naturally produce light then they don't count as Light-types. Only possible exception would be Diancie who I could see going either way
>but muh retyped moves
Replace retyped moves with other moves based on their types, problem solved. Buff Leaf Tornado, Silver Wind, etc if you need to
Only retyped a small fraction of mons and moves on the assumption that the rest would be brand new. I may have missed good candidates.