Diamond foil Walle is quite lucky, only 2% chance for the diamond card with a creature inside. (2% for diamond empty cards as well, but you won't be able to capture one of the 4 starters in the game - or switch what creature you have in what card) You also have 2 empty fire type cards in case you didn't notice! (you didn't mention it in the post when you mentioned the water cards)
Zappit is not radiant, the radiant version is slightly more yellow!
About your forest items, those are only required for your forest healer class, you're not forced to have to use Wrackoo with the forest healer, but it will provide a small synergy - i.e. not the end of the world if you don't get wrackoo, forest healer and water creature can have a nice synergy too since healer synergy provides both a boost to your grass/bug creature but also a small defense/resistance against grass/bug creatures, meaning your water creatures will be a bit less susceptible vs grass and bug if you plan on leveling them "the hard way" which gives you the highest rarity score upgrade boost upon level up.
I was pretty sure about the Walle that it was diamond foil, but not sure at all about Zappit. Seems like I'll need to see more of them to distinguish the radiant version.
The class is determined by the healer, right? If we won't have healers until later, for the initial public access for holders of alpha vials (if that's still planned) what class will we have? Or we will have a default healer to use of a certain class? And all progress in-game to be reset when beta arrives, if I remember well.
Either way, congrats to you and the team for what I've seen so far! I'm looking forward to the game.