>>525850011. Know the offensive and defensive typing of a raid mon, as well as something that won't get surprised when the raid mon has a coverage move like samemence with earthquake.
2. Bring a pokemon that counters the raid mons stat weakness, special attacker for a special defensive weak mon and vice versa
3. SELF BUFFING MOVES. The raid boss will clear its own debuffs and become immune to status when the shield goes up, if you can't buff yourself or your allies after the shield goes up your dead weight.
4. BE SURE THAT YOUR POKEMON ARE AT, OR HIGHER LEVEL THAN THE RAID MON. Bring a fresh caught lv70 to a 5 star raid ruins everyone's chances of winning
5. DO NOT USE BELLY DRUM IF YOUR POKEMON WILL DIE IN ONE HIT AFTERWARDS. belly drum is fine if you can tank a couple hits while setting up or heal yourself before attacking, but I can't believe how many times I've seen people bring Iron hands into a raid, belly drum twice and die. Swords dance is a tm, please use it.