Trouble initializing a struct array
If you use default values in struct declaration, you have to define also constructors for setting specific elements:
struct Amiibo
{
  const char *aName{};
  const char *ID{};
  const char *AudioFileName{};
  bool alreadyPlayed{false};

  Amiibo() = default;  // default implementation for default constructor
  
  Amiibo(const char* name, const char* id, const char * audio)  // constructor with three c strings as parameters
  : aName{ name }
  , ID{ id }
  , AudioFileName{ audio }
  { ; }
};  

Amiibo amii[] = {
      {&quot;Mario&quot;,&quot;A5005B00&quot;,&quot;MARIO&quot;,false},                     //0
      {&quot;Meta Knight&quot;,&quot;A5 00 02 00&quot;,&quot;MK&quot;},                     //1
      {&quot;Inkling&quot;, &quot;A5 00 05 00&quot;,&quot;INK&quot;},                       //2
      {&quot;Donkey Kong&quot;,&quot;A5 00 01 00&quot;,&quot;DK&quot;},                     //3
      {&quot;Lucas&quot;,&quot;A5 00 0A 00&quot;,&quot;LUCAS&quot;},                        //4
      {&quot;Duck Hunt&quot;, &quot;A5 00 08 00&quot;,&quot;DUCKH&quot;},                   //5
      {&quot;Ocarina of Time Link&quot;,&quot;A5 00 01 00&quot;,&quot;OOTL&quot;},          //6
      {&quot;Breath of The Wild Link&quot;,&quot;random&quot;,&quot;BOTWL&quot;},           //7
      {&quot;8-bit Link&quot;,&quot;random&quot;,&quot;8BITL&quot;},                        //8
      {&quot;Toon Link&quot;,&quot;random&quot;,&quot;TOONL&quot;},                         //9      
      {&quot;Mr. Game and Watch&quot;,&quot;random&quot;,&quot;GANDW&quot;},                //10
      {&quot;Falco&quot;,&quot;random&quot;,&quot;FALCO&quot;},                             //11
      {&quot;King Dedede&quot;,&quot;random&quot;,&quot;DEDEDE&quot;},                      //12
      {&quot;Mewtwo&quot;,&quot;random&quot;,&quot;MEWTWO&quot;},                           //13
      {&quot;Captain Falcon&quot;,&quot;random&quot;,&quot;CAPF&quot;},                     //14
      {&quot;ROB&quot;,&quot;random&quot;,&quot;ROB&quot;},                                 //15
      {&quot;PAC-MAN&quot;,&quot;random&quot;,&quot;PACMAN&quot;},                          //16
      {&quot;Cloud&quot;,&quot;random&quot;,&quot;CLOUD&quot;},                             //17
      {&quot;Ness&quot;,&quot;random&quot;,&quot;NESS&quot;},                               //18
      {&quot;Ryu&quot;,&quot;random&quot;,&quot;RYU&quot;}                                  //19
};

Btw on the older AVRs all those strings will resides also in memory