I've been having massive trouble dealing with them and I've been trying to level up so many pokemon to level 100, but hardly ever helps since most of my pokemon keeps getting one-shotted. At this point, I'm desperate to even borrow Pokemon. I'm willing to pay with stones, U-balls and some shinies, but tips on which pokes to use and what moveset is also greatly appreciated. Also, I'll screenshot my current team as well as the level 100's that I have if that helps. The Azelf is the only Pokemon that isn't level 100 yet.
My tips would be to have a few priority moves like aqua jet or bullet punch on Empoleon and Scizor. Sometimes challenges like this need a bit of luck in your favor like a critical hit or paralyze hax(meaning in some situations if you know you needed a miss or glitch bug, you could always run from the battle and try again.. I would try replacing moves that have only 5 PP (if you got any) because PP is crucial in this challenge. I took a Swellow for my flying type because of the speed. If you need further assistance on team building and what is most effective during each elite four member, check out Stuff of Legends Youtube video of the "How to beat the Elite Four". The guide was very helpful by watching someone beat the challenge and reassuring that it is possible to complete. Keep trying brother. P.S. i used Empoleon, Torterra(champ rank), Mamoswine, Cacturn, Swellow,and Ninetails to beat the elite four and it took me a few days of grinding to find the right procedure.