Summon Gate Guardian right away. Don't destroy Yami Yugi's monster, and don't summon or set any other monster with low attack unless you plan on using White Elephant's Gift right away. Yami Yugi's Phantom Beast Rock-Lizard will destroy it, inflicting 500 damage to you and lose you the duel. Pass the turns and use the draw cards, perform fusion summon and setting at least 1 Spell Reclamation before the last turn. You can use any normal monster that you have, it doesn't need to be glossy.
Summon unhappy girl as soon as you can, and pass the turns to stall the duel. Get BEUD out before the last turn and leave a monster slot open for vassal. Use vassal and union attack combo on the last turn.
If you don't have union attack, you can use Cu Chulainn with Blue-Eyes White Dragon, ritual weapon and riryoku instead.
On the cerberus skill set, it said that you could use sorcery conduct to use cerberus against Yami Yugi. Isn't Yami Yugi the only one that learns sorcery conduct? And if so, I don't think you can have Yami Yugi vs Yami Yugi as a gate battle.
You can use joey wheeler if he has draw sense light
I use cerberus to farm Yami Yugi, but I do it differently. I summon gravekeeper's vassal on the last turn and do the secret pass + union attack combo. Most of the time I need draw sense light to trigger before I can get a cerberus in my hand.
i think it will more interested when i can fight my own deck, just to make sure anyone have same idea. becouse fight legendary duel with same card deck without customization make me bore, repeat deck and i win, at all