Tornadus-T and Thundurus-T have very different strengths. Tornadus-T has a hugely important 20 extra base speed, significantly better bulk, and Regenerator, all of which make it a wonderful pivot (also Flying STAB is nice). Thundurus-T has that huge base SpA stat and a great electric typing, but is really frail, which makes it much more suitable as a wallbreaker or sweeper than a pivot like Tornadus. It also doesn't synergize as well with Terrakion, since it can't immediately threaten the Grass and Fighting types Terrakion has trouble with due to its lack of a Flying attack. People smashing Entei, you're not taking into account that 50% burn chance. There is practically nothing (the exceptions being relatively bulky Fire types) that wants to switch into a Sacred Fire and risk a burn, and most of those are covered by one or both of Stone Edge and Bulldoze. And then there's the obvious ExtremeSpeed to also set it apart from stuff like Infernape and Darmanitan. Plus, it can take a hit (and yes, Bug, Fire, and Fairy resistances really are useful). Homeslice, I like Mamoswine and Raikou as members of a core, however, I'm not clear from your explanation on why they work well together. Could you help me understand a little better? Psyco Josho, that's a really cool idea and I look forward to seeing suggestions of possible cores we could make with your framework!