Summon The Unhappy Girl and start locking Yugi's monsters, prioritizing Guardian Statue so he can't flip summon it, then on to high attack monster. Afterwards you can either keep passing the turns and use Abyssal Designator on the last turn, or summon monsters to attack to force Yugi to use his sphere kuriboh. When you have 0 cards left, perform your high damage combo.
It's important to keep in mind that Yugi will start to attack your unhappy girl if their total damage after attacking unhappy girl is greater than your LP, so try to keep it high and not use abyssal until last turn.
Dinosaur & BEWD
This is a deck for very new players who started playing Duel Links since the recent Pegasus unlock event. All the cards in this deck are F2P, and you can still reach 5000 score by using 3~5 glossy cards.
With the Dinosaur Kingdom skill, most of the dino monsters can handle Yugi's monster because of their high attack. This is a more easier deck to build since it uses easily obtainable cards, but it can be more difficult to pull off since Yugi has sphere kuriboh, castle walls, and union attack. Use your spell/trap cards to handle those situations and keep destroying his monsters. Perform ritual and tribute summon, and end the duel with blue-eyes with an increased attack to get over 3,000 damage bonus.
If you don't have labyrinth builder skill for the paradox bros., here's the deck I'm using for the Yugi lv.30. Unhappy Girl + Piranha (Holy Guard). It's easy to use. Make sure to activate your etaqua for the +100 points in your last turn to achieve the 8k points.
Since Yugi lvl 30 didnt use Order to Charger, this deck should works perfectly...
If you consist attack his monster, he will use his first kuriboh. And remaining will be taken out by combo Goblin Remedy + Abyssal (give your 1000 points by life on the brinks).
To prevent your monster is destroyed by Yugi, I recommended to use Etaqua, Enemy Controller, or Sphere Kuriboh. And then, to make sure, add Magic Jammer or Magic Drain to negate Union Attack...
Make an improvise when you dealing with unpredictable situation... Good Luck
I'm not wrong, it happened to me in my first duel. I used skill to summoned the Labyrinth Wall and set Dimension Gate in the first turn and banished it the turn after that. Several turns later Yugi managed to summon his Valkyrion and attacked me, then I chose to send the Gate to the Graveyard to bring the Wall back. He attacked and destroy my Wall. Then I lose in the turn after that.