Yeah, I was planning on starting with Oshawatt and only using it. Since Timid, Modest, Calm, and Bold are all seen with either HP Ice or HP Flying spreads on Thundurus and Thundurus-T in VGC, I'm thinking I'll pick one of those Hidden Powers, find an IV seed for it, then find the number of Chatters necessary to hit each of those 4 natures (and the corresponding PIDs). That way, I can restart and RNG my ID/SID anytime for a quick and definite shiny with any of those natures without having to play through twice each time.