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As someone who has used the second core I can say it's definetley worthy of going in the archive. Bisharp and Mega Sableye have excellent synergy. I would however slash lum berry for bisharp's item, particularly if your using swords dance, to ease your time setting up.
Mega Aggron for C: Loose some weight...
Alakazam for B: Spoons are intresting, but I've been a huge fan of hominid pokemon. He also needs to learn to shave.
Mega Beedrill for B: The eyes are scary, but for the most part it's just a bigger Beedrill with bigger points.
Mega Blastoise for A: What's...
Salamance for A: I know it's generic buts it's simply and intimidating.
Suicune for A: It's really graceful, and has an excellent colour scheme to represent something that gaurds nature.
Crobat for B: It's got an ugly face, but it's wings and colours fit it quite well and save it from being in...
I actually suggested Hydreigon a while back, but it was rejected by the council, so not sure what's changed.
Anyway:
Hydreigon: Yeah... This is essential a stronger, bulkier greninja with a even more scary movepool in exchange for having much less speed. The reason I would much rather use...
Wall breaker Lando-I-S
Choicd Scarf Gengar-A
Swords Dance gliscor-A+
Rock Polish mega diancie-A+
Calm mind mega Sableye-A+
Utility Mega Sableye-A+
Life orb offensive clefable-A-/B+/B
Magma trapper heatran-A+
Dragon dance mega Gyarados-A+
Wall breaker thunderus (defiant)-A+
Choice specs latios...
Mega Glalie dropped becuase it was weak to stealth Rock, had a horrible defensive typing, lacked bulk, had the 4MSS (choosing between hitting heatran with equake and wash rotom with freeze dry) and at most, would last about 3 turns. It wall breaking capabilities were enough to keep it ranked...
Probaly Landorus-I as its really good right now, and In know that a few people want it suspected. However, their most likely just going to suspect test mega Metagross again...