Without even attempting to give you an advice, I would severely push the ratio in favor of BTC.
I would tell him to stay only with bitcoin
Yeah, I didn't want to be that strict, but you are right. In fact, the only use for these pump and dump coins is to accumulate more BTC, but this requires some trading skills.
Pump and dump coins do not require skill, they either require luck that you invest in a coin before it is pumped by one of those groups out of luck and that you recognize what it is happening or that you somehow get access to privileged information about what coin the leaders of those groups are going to select to pump, just be careful because in some jurisdictions pump and dump groups are illegal.