@Darkanine. I'm gonna paraphrase myself.
Most 2-Stage final form Pokemon wind up at 8-A. 2-Stage final form Pokemon wind up being TLCLs via being able to mega-evolve (Slowbro, Houndoom, Glailie, etc), having scaling to support it (Wailord, Milotic, Goliscopod), by being late game acquired Pokemon that evolve late, which is normally meant to signify some reward (Bisharp, Braviary, Mandibuzz, Crabominable) came from an 8-A already (Yanmega, Probopass, etc.), if they're normally seen as incredibly powerful (Arcanine, Ninetales [becaue she scales to Arcanine], or Vespiquen), or they're hyped up like crazy (Zoroark, Lycanroc). Same applies to Stage Pokemon. Mega evolve (Absol, Kangaskhan), Scaling to support (Dhelmise, Wishiwashi School Form), N/A for the next two, Seen as incredibly powerful (Spiritomb, Rotom)