The spiders are actually more accurate than they appear. With one or two individual spiders using Latch On, you can bring high defense down to manageable levels. I've seen something similar to this in another thread:
For instance, take Lilith at Def 8. Activate Ramos, do whatever, and Link In a swarm. Move the swarm near Lilith and make it's two free attacks (we're ignoring Disappear for the purpose of this experiment), then scatter. If you positioned the swarm right, you should be able to put two of the spiders in btb with Lilith. Ramos' companion carries over to the little spiders, who are all slow. First, the spider that isn't in btb walks, and then uses Latch On, which brings Lilith's Def down to 6. Then, one of the others goes, latches on (making her Def 4) and attacks. The last one gets to swing at Lilith at Def 2 after it latches on.
I haven't played enough games to know if it works as well as it looks like it would, but I'm certainly going to try it out when I can.