Wanted to add something i found out:

In PVP, when you get to rank 10, the game gets much harder. You now go second, and the opponent has lvl 20 legendary cards (the whole deck).

The opponent's card is already OP, and it will either get a fusion, or a second card. It will then destroy your card and crush your life points the next round. If you have obtained this rank like i have, dont feel bad when you get knocked back down to 9.

I dont think its likely anyone can beat it without spending alot of money (and luck) in getting legendary cards.