i like to name my Pokemon after moves, or sometimes abilities, or other references.
for example,
Deino-Hustler
INfernape-Heat Wave, etc.
I'm thinking for solgaleo, iron head, for jangmo-o, Head-BUTT, mimikyu- hex, rowlet- leif, type:null, (if he can learn this) body-slam, rockruff(the exception), THE ROCK