The way I play suicidal, I go berserker for the first two or three waves and go "solo" searhing for weapons and ammo on ground. The weapons I find I sell, and since zerker doesnt require much money its a great way of saving up for later waves to buy eg. Scar/Ak if you are planning to go commando. And since you cant be grapped by clots, and you are fast, it shouldnt be too much of an problem to run around the map in the beginning. And of course its better being lvl 5-6 so you spawn with a weapon and/or armor.
Altho, often I spend my whole game playing as berserker and give all my extra money and weapons to my teammates. Everyone seems to think its the worst perk for suicidal, but imo its one of the easiest ones to play because you get katana after wave 1 on level 5 and you dont need to buy ammo. The only problem will be fleshpounds rly, if you know how to avoid crawler/siren/bloat attacks. And you know, berserker can actually kill a fleshpound on solo suicidal

, but for 6 man game it takes a bit more effort and help from teammates...
I have done the same thing as Hateme on this, Zerker is a great wave 1 perk. Starts with armor, and uses no ammo if you know how to kill bloats without getting hit. I normally use zerker for solo play tho
As for group, I use an SS simply because, you wont find ppl running around the map (or at least I hope not) and they will stay in one spot. So I use my SS and Xbow to get through the first wave, then switch to what I need to. If I want to stay SS I would just use my 9mm and save my Xbow ammo
As for pat, there are alot of tactics ppl use, but to my imo, there are only 3 reliable ones.
I termed them as: Fire Fest, Tank and Spank, and Vigilante Justice
Fire fest: is having all 6 players go Support and use AA12 or go SS and use the M14. The tactic after switching would be to lock him in the room via welding the door or body blocking.
Tank and Spank: is haveing all 6 players go medic with Xbows. The tactic after this will be attempt to get everyone to shoot pat when he enters to room and use up his heals. The medic can take his hits, so when he comes back in the room, everyone fires again, and makes him leave. Repeat this process till he is dead.
Vigilante Justice: is having all 6 players use zerkers minimum lvl is 3. The tactic after this will be to surround pat so he can't heal, use the saw and alt fire him till dead. If you are push away, get back in the circle fast, or team must fill the gap for this to work.
I personally like the zerker tactic. When used on suicidal the fastest time I have had on pat was about 5 sec. everyone just jumped on him and he was dead.