First, the ramp and mana fixing
Is stock guaranteed after a successful pre-order
Like most Pokmon cards, the value of Applin depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Prismatic Evolutions)
It can't take advantage of cards like Zur the Enchanter, and you can't cheat it out with cards like Brilliant Restoration (well, you can, but you still have to unlock the doors)
Tribal spells work like any other spell
It gets a blocker or other annoying creature out of the picture and grants a potentially sizeable buff to Commander Damage