These cards feature Pokmon from Gen IV and introduced LV.X (level-up) Pokmon, which are stronger Pokmon than normal
It means Master will do great work in an Anowon, the Ruin ThiefAnowon, the Ruin Thief Rogue typal deck and it also buffs important creatures in your deck that don't actually have the Ninja creature type, like Slither BladeSlither Blade
By letting it enter play without its coming into play text taking effect, you could sneak a 12/12 into play for a total of one mana for the Dreadnaught and two for the Mask
For white, we have destroy target enchantment, or Disenchant
You can also run it fairly, as a commander that provides both a mana advantage and card advantage since it effectively copies your instants and sorceries and gives you a discount
Then, of course, it got banned in Standard and Pioneer