You need at least radvd. Router advertisements communicate to devices on the network what the default gateway is and what the network configuration is. You always need that.
The router advertisement can tell clients whether they are allowed to choose their own addresses or not (auto configuration). If you allow this then you might not need DHCP at all.
Then you can add DHCP, either stateless or stateful. Stateless DHCP tells clients configuration options like DNS resolvers etc without providing addresses (useful if you allow auto configuring). Stateful DHCP also provides addresses.
As you need radvd anyway it's the easiest, possibly combined with stateless DHCP. Don't bother with stateful DHCP unless you really need to manage addresses manually.