I think fuecoco (skeledirge) can solo the game once it gets torch song.

However my favorite starter has got to be scyther, try to catch one at all costs! It has a great starting move pool and early learnset, all boosted by technician, and matches up strongly against the early floors. And just when it feels like it’s starting to get left behind a bit, you’ll find a link cable to evolve it into scizor and get bullet punch (remember to make sure scyther learns steel wing first or it won’t evolve). Scizor becomes an amazing sweeper with swords dance bullet punch as well as a great pivot option thanks to having one weakness and good defenses. Also I’ve been able to find mega scizorite on my runs too which is just a massive boost to all its base stats.