Well, Guts vs Alex is a definite win for the former. Guts swings that blade with incredible speed and strenght. But Berserker vs Thorn? That kind of fight would have a really dubious outcome. Alexander can't really die with the Thorn as he regenerates instantly. I think the Berserker vs Thorn would be 30-70, leaning on Thorn Alexander's victory.
Considering Paladin Anderson's bayonnets are effective only against vampires, Guts shouldn't have much trouble battling him with and without the Berserker Armor though I wouldn't be surprised if tossing endless bayonnets causes their battle to be prolonged. But against a Helena's Nail powered Anderson, Guts is screwed. Besides instant regeneration from attacks, the vines from the Nail have the power to set anything unholy ablaze if they restrain their target and considering the cursed nature of the Berserker Armor, this scenario would be in the favor of Anderson.
Guts has been zapped by lightning once and set ablaze by a spirit-deity of Fire and War. The Nail ain't gonna have much affect on him. Guts got inches from the Godhand, the pain of which through the Brand should've done more than kill a normal person, yet he didn't even lose consciousness and still attacked Femto in the Godhand's own realm. With Berserker armor, Guts is much too fast for Anderson, nevermind his sheer strength and tenacity. Anderson will be torn to pieces and crushed into pace.