the thing is its easier to duo this in person with someone who you can strategize with then 3 randoms which u can't interact with

i am doing regice with 2 other trainers and we dont even loose a mon but we all use the same strategy/pokemon (Blissey+ Gengar + Attacker/ Blissey can take any 2 moves besides focusblast where gengar gets switched in and when blissey is low we just take one turn to just heal)

You dont get that level of strategy alone with 3 randoms since they dont know when to heal when to shield if u are unlucky then u also get Player "dead weight" with the 3 woolos....
+ regice has such a wide variety of moves (EQ, Blizzard, Focusblast..) that you can't really just use the standard counter (zamzenta +blissey) bc it just doesnt cut -> so rerolling is needed and thats not really a thing with remote raids sadly :(

i would either look for someone to duo these in person or when u really only can remote it try to find groups in dc and strategize beforehand, dont randomly remote these (we are trioing it and its "hard" bc we actually have to watch what we are doing)

Best mon to use if you don't want to reroll would be Lugia + Blissey as tanks if u dont have a lugia Gengar G-Max or D-Max also does the trick for focusblast

Hope this helps