It was possible to build a manabase that would support blue mana nicely (twelve rainbow + three Spirebluff Canal), but black and white had to be ignored a bit in the process
As a creature, Mirkwood Bats is a little underwhelming: a four-mana Black 2/3 with flying
The Steel Apron Pokmon Tool not only makes the Pokmon take 10 less damage, but also remains unaffected by any Special Conditions (no Poison, Burn, Paralysis, Sleep, etc)
At common, cards with exhaust abilities, like Stampeding Scurryfoot and Prowcatcher Specialist, gain significant value in red-green decks
Its also cheap since its underplayed which makes it a great strategy in casual pods where your opponents arent winning on turn 4
However, aside from the switch (or button) itself, this card heavily features a floating Pokeball as its focal point, explaining the card's value