The most common attackers in these decks are used to hit for Weakness, like Shuppet () to hit Psychic Weakness, Dunsparce () to hit Colorless Weakness, and Mankey () or Relicanth () to hit Fighting Weakness
"Commander ninjutsu [cost]" means "[Cost], Reveal this card from your hand or from the command zone, Return an unblocked attacking creature you control to its owner's hand: Put this card onto the battlefield tapped and attacking." Commander ninjutsu is a variant of ninjutsu that can be activated from the command zone as well as from your hand
This has its pros and cons, and there's some discussion to which extent you can force some archetypes and trick them into getting your lane open
To keep the flavor, a more appropriate translation might be "Eeney", "Meeney", "Miney" and "Moe"
Boots occupies the same niche as Greaves in that it provides protection for your monsters