Summon Unhappy Girl, or Rai-Mei if you don't have unhappy girl, and stall until you can perform gravekeeper's vassal and union attack combo. Set a Rai-Mei when you set an Enchanted Javelin to raise your LP to ensure Tea won't attack the unhappy girl while also thinning your deck. Summon BEUD when you can before the last turn and leave 1 monster slot open for vassal.
Example deck (No Union Attack)
Works similarly to the method above, except the finisher is Cu Chulainn. Use the Rai-Mei to thin out your deck and summon BEWD early in the duel. Since Cu Chulainn's damage is only going to be around 5000, make sure to destroy her solemn wishes as early as you can, otherwise just deal the 5000 damage and get her to deck out.
Im using elements unite for tea level 40 and it's always 100% win with 8k assesment so if someone wants I will post deck,it's very cheap
Important things for Tea
1.Don't attack with Gate guardian her monsters because she have 3 skelengel copies and she will deck out quickly.Also she have 2 copies of cards from the sky so deck out is problem for her,you must put all possible cards to deck your cards fast.
2.She have 2 copies of trap solomns wishes (it hates me to check spelling) so it will be problem if she activate both early so for example spell card remove trap could be added but I don't use it