You could name them all after a group (i.e. famous rock stars, Oscar winning movie stars etc). But I always like Spanish names, maybe all starting with the same letter? Pablo, Paco, Pedro, Pancho, Paloma, Paz, Palma, Princesa, Priscila. Otherwise for chihuahua's I'd go with big dog names like Rex, Kujo, Killer etc. Keep it fun!
I have named mine Charlie Brown due to his coat and punitive stature as well as his overall demeanor. Celebrities commonly name there's cutesy puppy names, sugar, lovey etc. Take time to judge their personalites differently, the name is supposed to reflect that.
Elena, Georgy, Sunshine, Cookie Dough, Dolly, Sandra, Jose, Luis, Kelly, Baby, Dora, Ivan, and Tori are all good names to me, but it's really up to you.