Fun fact, this question gave me the motivation to finish a Violet playthrough of mine, so thanks I guess.
Anyways, the answer is No.
I tried not Terastalizing, Terastalizing in the battle, trying to waste my Tera before the battles (it got recharged somehow), but nothing worked, the partners do not Terastalize their Pokemon.
Also, they didn't send their aces out last for me, the order the mons where sent out changed between battles except the leading Pokemon but they didn't send the aces out last.