Scurry of Squirrels

If the defending player is your only opponent, no tokens are put onto the battlefield.

The tokens created by a single instance of myriad all enter at the same time.

Each token copies exactly what was printed on the original creature and nothing else. It doesn't copy whether that creature is tapped or untapped, whether it has any counters on it or Auras and Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on.

Although the tokens enter attacking, they were never declared as attackers. Abilities that trigger whenever a creature attacks won't trigger, including the myriad ability of the tokens. If there are any costs to have a creature attack, those costs won't apply to the tokens.

Any "enters" abilities of the copied creature will trigger when the tokens enter. Any "as [this permanent] enters" or "[this permanent] enters with" abilities of the copied creature will also work.