Are there any ghost types that would be a good partner for a beginning trainer?

Phantump.

I hope you realize you’re a terrible person, even if you do give to youth-focused charities. —LH

Edit: First and foremost, I could have said dhelmise, but I did not.

In all seriousness, anonymous, short of the notoriously difficult to handle pokémon (namely spiritomb and dhelmise), practically any ghost-type may be an excellent partner for beginning trainers. The only thing about ghost-types is that quite a few of them require patience to raise. For example, both gastly and misdreavus are known for their mischievous sides, but if a trainer is constantly vigilant and establishes clear boundaries early on, handling either species isn’t outside the capacity for even a beginning trainer.

Moreover, some pokémon—such as litwick and honedge—can be quite dangerous if handled improperly. (Never touch either a litwick’s flame or a honedge’s hilt, even if the litwick or honedge themselves are friendly with you.) However, so long as you know the physical dangers of a pokémon, it’s fairly easy to avoid them. And in any case, the truth is that ghost-types are no more dangerous than fire-types, so by all means, never let this warning scare you away from the type.

If we must narrow it down, yamask tend to be the most responsive to human commands, although training yamask can be a bit of a taboo to certain cultures (given the fact that some people believe yamask are human spirits incarnated into pokémon form). Alternatively, duskull is generally docile; it’s not known for either the mischievous streak or the possessiveness (no pun intended) of some other members of the ghost type. Pumpkaboo likewise is relatively easy to train, as are frillish and golett. But above all, gastly tends to be the most popular, in part due to its ready availability and in part because they’re quite affectionate and eager to please once one gets past their prankster sides.

And of course, there’s also phantump, but these carry even more ethical questions than yamask, even if they are possibly the easiest to train ghost-types one can catch.

Finally, should anyone ask, dhelmise itself is not that difficult to train either. It’s just that it’s a seaweed pokémon that prefers wrapping itself around anchors meant for cruise liners, and thus, they are quite literally difficult to handle. For comparison’s sake, starting your journey with a dhelmise would be very much like starting your journey with an onix: it’s not impossible, but quite frankly, you may wish to consider saving yourself (and Nurse Joy) a headache by starting with something smaller.