Pursued Whale — ruling 1

If a creature affected by the Pirate token can't attack for any reason (such as being tapped or having come under that player's control that turn), then it doesn't attack. If there's a cost associated with having it attack, the player isn't forced to pay that cost, so it doesn't have to attack in that case either.

Pursued Whale — ruling 2

To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases (such as that of Pursued Whale), then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.

Pursued Whale : règles, fonctionnement et interactions (MTG)

Pursued Whale is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

When this creature enters, each opponent creates a 1/1 red Pirate creature token with "This token can't block" and "Creatures you control attack each combat if able." Spells your opponents cast that target this creature cost more to cast.

How it works : Pursued Whale

Original English text — Wizards of the Coast / Scryfall

#1June 23, 2020· Wizards of the Coast
If a creature affected by the Pirate token can't attack for any reason (such as being tapped or having come under that player's control that turn), then it doesn't attack. If there's a cost associated with having it attack, the player isn't forced to pay that cost, so it doesn't have to attack in that case either.
Card named in this ruling
Pirate
#2June 23, 2020· Wizards of the Coast
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases (such as that of Pursued Whale), then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.
No other card is named in this ruling.