Hello I just joined up because I have in possession some Pokemon cards that are quite old and in very good shape and I would like to know what I have

I have holographic cards dated 1998 and 1999 ,2000. A magneton 1999,Aerodactyl 1999,Venusaur1999,Haunter 1999,Gendar 1999,Lt. Surge's Electrobuzz 1999 2000,Dark Charizard 1999 2000, Dark Gyarados 1999 2000,and a Charizard 1999 that also has a little foil dot in the lower left corner. My son collected these back then and they have been kept in sleeves since they were new ,never played. There were a lot more but I gave them to a kid that was into them but my son thought these were special so I kept them. I thought on a forum like this someone could tell me if they're worth something and what to do with them.