As it is, it took three STAB Double Kicks from Specs to put the damn thing down, and it was dealing a good bit of her health each hit
SR Super Rare Groza, Tyrant of Thunder X DARK Level 8 [ FiendSynchroEffect ] ATK 2800 DEF 2800 1 Tuner + 1+ non-Tuner Fiend monsters During your opponent's Main Phase (Quick Effect): You can target 1 Effect Monster on the field
That said, you can access 7 of your 15 cards in your sideboard in best-of-one matches using special cards like Invasion of Arcavios, Fae of Wishes through the Granted mode to look for cards outside the game cards in your sideboard are considered to be outside of the game and similar with special mechanics like lesson and learn from Strixhaven
2021-03-19 As you activate a ninjutsu ability, you reveal the Ninja card in your hand and return the attacking creature
See rule 602, "Activating Activated Abilities." Therefore, once you put the Activated Ability on the stack, it stays there unless it is countered or something specifically removes the ability from the stack
