Riolu

Riolu (90/185), the Common from Vivid Voltage, has an estimated ungraded market price of about under $1. Note: 28 other cards named Riolu exist across the sets Riffle tracks, at very different values; check the collector number.

This page covers Riolu (90/185), the Common (about under $1) from Vivid Voltage.

The other versions: #215/198 from Scarlet & Violet (Illustration rare, about $33–$44); #60/95 from Unleashed (Common, about $17–$23); #91/127 from Platinum (Common, about $15–$20); #173/91 from Paldean Fates (Shiny rare, about $13–$17); #61/130 from Diamond & Pearl (Uncommon, about $10–$14); #GG26/70 from Crown Zenith Galarian Gallery (Rare, about $10–$13); #75/135 from Plasma Storm (Common, about $9–$12); #50/95 from Call of Legends (Uncommon, about $8–$10); #117/146 from Legends Awakened (Common, about $6–$8); #79/113 from Legendary Treasures (Uncommon, about $6–$8); #76/135 from Plasma Storm (Common, about $3–$5); #63/99 from Next Destinies (Common, about $3–$4); #66/156 from Ultra Prism (Common, about under $1); #115/236 from Unified Minds (Common, about under $1); #116/236 from Unified Minds (Common, about under $1); #45/124 from Fates Collide (Common, about under $1); #70/147 from Burning Shadows (Common, about under $1); #102/214 from Unbroken Bonds (Common, about under $1); #46/124 from Fates Collide (Common, about under $1); #071/159 from Crown Zenith (Common, about under $1); #050/131 from Prismatic Evolutions (Common, about under $1); #076/132 from Mega Evolution (Common, about under $1); #081/142 from Stellar Crown (Common, about under $1); #113/198 from Scarlet & Violet (Common, about under $1); #112/198 from Scarlet & Violet (Common, about under $1); #078/172 from Brilliant Stars (Common, about under $1); #112/217 from Ascended Heroes (Common, about under $1); #SV21/94 from Hidden Fates Shiny Vault (Shiny rare).

The collector number printed at the bottom of the card is the reliable way to tell them apart.