Magikarp 129/165 refers to the Magikarp card from the Japanese expansion Pokémon Card 151 (SV2a).
This is a C (Common) rarity card. Depending on the specific variant (foil/holofoil type) you have or are looking for, its market value varies significantly:
Master Ball" Mirror Foil Version
- Features: A highly coveted holographic finish featuring the "M" logo Master Ball pattern. Note: There is only one random Master Ball card per booster box, making this variant extremely rare and highly collectible.
- Shipping 3days