You want to get to 8 mana for activating Svella
Be sure to check out my other cards
In: Nashi, Moon Sages Scion Out: Sheoldred Whispering One In keeping with the decks theme of using other players stuff, Nashi does the double duty of also exiling cards
The most valuable Rayquaza cards typically include 1st Edition holographic cards from early sets, Gold Star variants, Alt Art cards from modern sets, and promotional cards with limited distribution
Instead of looking at buying this expensive Magikarp, you could opt to chase cards in the newest Pokmon set - Prismatic Evolutions
The difference between a grade 9 and a grade 10 can be tens of thousands of dollars, so a beat-up Base Set card from your attic isn't likely to be a winning lottery ticket