4-6 Boosters: Donphan Prime and Magnezone Prime This is where the market tends to fluctuate
Note that if you really want to get hold of Ariel, Sonic Warrior for your deck, the standard, Ultra Rare card is selling for just $3 , so you dont have to break the bank unless you really must have the more spectacular version of the card
For the secondary market, the impact on existing sets is minimal BOX prices are already set by supply and demand, not MSRP
In a couple of turns this can become a 6/6, and blocking with it, then tapping before damage is also something you can do
That does not mean this is necessarily good, since the Ouroboroid effect is likely much better in an aggressive deck
Some will have some really cool shit, some will have nothing xD (I literally found a Rayqauza Poncho Box in a store) They can be crazy