My a couple thoughts on things: Gravity: Well, I dont really know how we could build a mon that abuses gravity better than landorus, realistically ou is aggressive enough that the buff to spikes/tspikes isnt enough, so were looking at purely the useful offensive things of gravity. It gives a temporary boost worth less than +1 (blizzard vs ice beam is less than +1, etc), but this is really not very useful. Then it gives a boost to ground moves in removing their immunities, but again this is just not that useful. There already are pokemon built perfectly to abuse gravity that learn it, and yet they still essentially never run it because its just not worth a spot. Explosion: Again, i don't think we could make explosion very good. Its resisted by about a quarter of ou, and a lot of top pokemon, and just isnt that strong. So basically up until the very late game, theyll have an easy switch in to it, and since this mon should be built around this move, it would be absurdly predictable. Yes, we can try to make it so we can combat the things that switch in on explosion, but even then when it comes down to it, explosion is incredibly prediction heavy. the problem with explosion is how costly it is to get it wrong. Its an extreme risk, and yet its still not even particularly likely to pick up a KO with correct prediction unless we have great attack, and if we have great attack you can almost certainly ko with some other move.