Right now a search for Pokemon Swirl returned nearly 3000 listings that include the term
This allows, for instance, several damage-doubling replacement effects to stack multiplicatively, or for a friendly replacement effect to reduce incoming damage before the opposing replacement effect doubles it
Legality depends on the tournament format -- Hero Token can be legal in some formats and banned or restricted in others
Pretty good, considering Swallow Up, its next move, costing 3 Water and 1 Colorless, will inflict 50 damage plus another 50 if the defending Pokmon has less remaining HP than Wailord
To make matters worse for your opponent, add 2x Nihilego in your deck to contribute 20 more damage to poisoned Pokmon, making it a glorious 70 chip damage overall
If you drew a monster that shared an attribute with the monster discarded: Draw 1 card