This is one of the ways to defeat lance.

My method only needs two [Level.100] Pokemon: Gengar、Gyarados

 

Gyarados Set:

Move: Dragon Dance、Ice Fang、Surf

Equipment: Never-Melt Ice //just make sure one shot, It will be need more [Dragon Dance] if you don't have

 

Team Leader is Gengar and also a pioneer of death.

 

Script:

1. Face to Dragonite, let Gengar trigger the Cursed Body. //It have 30% Chance. If not triggered, log out and again

2. Switch to Gyarados and use [Dragon Dance] 2-3 times If triggered.

3.Use [ice Fang] until battle end. //You can use [Dragon Dance] once if the opposite side gets Frozen

Using shellsmash cloyster is much better than that, as you dont need to relog.....just my opinion though

what I need(i.e need to pay someone or what?) to battle lance in dragon dens?? after I defeat him, will I have access to ceru cave?

Using a scizor with swords dance, agility and baton pass would be better

Instead of gengar

What can be an alternative for gyarados