Traveling Chocobo's last ability affects a permanent's own "enters" triggered abilities (as long as it's a land or Bird you control) as well as other triggered abilities that trigger when a land or Bird you control enters the battlefield
At the moment it is not possible to choose which side to print, both sides will always be added in the PDF
But what makes this even stronger is the ability to stack your graveyard, too
Thankfully, zombie decks tend to be aggressive and raise enough tokens to utilize this card
Amethyst is found in many top-placing decks in Lorcana tournaments and is often paired with Amber or Ruby ink to create a Bounce Control deck archetype
Apart from fringe cases like Grim Tutor, they are all tried and tested in formats past, and we can assume that Wizards is including them here because the gameplay they created there is of a sort that the creators of the game want to see in the next few years of Standard