Shadowless cards were only around for the first two releases of Base Set
Nevertheless, if you can muster the three colors required for the War Monk, it's a great value for the price
To make sure your cards are easily accessible, you may want to create sections in your binder, use separate boxes, or use different drawers for each category you have organized your evolutions into
They also all have triggered effects that are downright nasty if you have remained the Monarch
This really just lowers demand for them as the side that made them special is just not that special, especially when other Foil tokens are being released as rewards all the time
Beyond this, the Pioneer format started at Return to Ravnica and spanned through to the present day's sets