Dropping a creature like Atsushi, the Blazing Sky with five lands then using the extra mana to give it haste is no small play
The ideal way to estimate the value of Pokmon cards is to consult resale platforms between private individuals and/or professionals (called "Marketplaces" - for example: eBay or TCG Player) and analyze the resale values for each card you wish to estimate
Ghyrson Starn, Kelermorph : Around $22 Shadow in the Warp : Around $17 Exalted Flamer of Tzeentch : Around $17 Keeper of Secrets : Around $15 Bloodthirster : Around $15 And They Shall Know No Fear : Around $13 Celestine, the Living Saint: Around $10 Resurrection Orb : Around $10 Biophagus : Around $10 All images via WotC
Legality depends on the tournament format -- Gornog, the Red Reaper can be legal in some formats and banned or restricted in others
This is one 1/1 not to be underestimated
Banding allows any creature with banding, and at most one creature without, to attack in a band. The band can be blocked by any creature that could block a single creature in the band