void ZROBEFEKT(struct efekt *); //* tutaj wyskakuje:
Multiple markers at this line
   - 'struct efekt' declared inside parameter list [enabled by default]
   - expected 'struct efekt *' but argument is of type 'struct efekt *'
   - its scope is only this definition or declaration, which is probably not what you want [enabled by
    default]
*//

struct efekt {
  uint8_t diody[1];
  uint8_t size;
  uint8_t time1;
};

int main (void) {

   struct efekt *wsk,jeden;
   wsk = &jeden;

   jeden.diody[0] = 0b00000000;
   jeden.diody[1] = 0b11111111;
   jeden.size = 1;
   jeden.time1 = 200;

   while(1) {
         ZROBEFEKT(wsk); //* tutaj:
passing argument 1 of 'ZROBEFEKT' from incompatible pointer type [enabled by default]
*//
   }
}

  void ZROBEFEKT(struct efekt * ptr) { //* a tutaj:
conflicting types for 'ZROBEFEKT'
*//
   uint8_t i,k;
   for(i=0;i<=ptr->size;i++) {
      for(k=0;k<=ILOSCDIOD;k++) {
         if(((ptr->diody[i]>>k)&(0x01))==1) ON();
         if(((ptr->diody[i]>>k)&(0x01))==0) OFF();
      }
      ZAPISZ();
      _delay_ms(ptr->time1);
   }
}