stats-wise, fully-powered Calvin is actually above average
However if you are going for Monster Mine you might want to keep in Gameciel, the Sea Turtle Kaiju
For the cost of two Energy (one Fighting and one Colorless), you can use an attack that does up to 100 damage, as long as you have damage counters on any of your Benched Pokemon
Use Fieldwork to increase the bonus of this investigation by +2 Use Fingerprinting Kits and Deductions to pull additional clues off locations
In Pokemon, that can include regular holo, reverse holo, and a bunch of modern shiny variants that no longer fit neatly into the old picture shiny vs background shiny split
The original ATK of this card becomes the combined original ATK of the materials used for its Fusion Summon