I already posted about the past 3 pokemon but ill summarize my thoughts on them, if you disagree, refer to my earlier post for a more elaborate explanation.
Dragon Dance Krookidle- I like the Dual STAB coverage it gets, plus the coverage moves it has to offer like stone edge, dragon claw, and brick break. The only problem is 117 Attack is low even boosted, while max speed investment at +1 still leaves it outsped by common scarfers, most notably Landoge, as well as mega Bee and Sceptile, both of which can threaten with their STABs. Running Jolly fixes that, but then you loose on some noticeable power. Still very appealing, but its problems begin to surface when you think about it.
Poison Heal Gastrodon-This one got my vote but unlike Krook, when i thought about it, it seems pretty broken. Its pretty much Gliscor, both have poison heal+reliable recovery to really troll, except Gastrodon has marginally better bulk thanks to its higher base HP, plus Scald aka the most annoying move ever. While it doesn't seem that bad, Gastrodon can go fully specially defensive, and still wall a ton of the metagame, thanks to its arguably better defensive typing, while scald will let it fish for burns to alleviate its meh base 68 defense. Even then you can go full defensive if you really want. Yeah it seems annoying, but thats because its a defensive theorymon and I'm a sucker for a defensive buffs in such an offensive metagame, so it will get my vote i guess.
Drought Typlosion- Poor Mans Zard-Y. Both have similar coverage, same Speed, but Typlosion can hold an item, being expert belt, charcoal, or specs, but isn't immune to flying like Zard-Y, but zard-y has a nastier SR weakness, so its a double edged sword. Not much else to say about this one, if you want Zard-Ys wall breaking powers and fantastic coverage, but want to use a different mega, this is the guy for you
but now for the new guy who wants to compete with these guys
Focus Blast Pidgeot- This guy is a different kind of bird spam. Rather than being a physical attacker, this guy relies on its 100% Hurricanes to destroy lives. The only problem is Pidegots coverage is ass, literally heatwave and hidden power. Focus Blast not only has perfect accuracy thanks to no guard, but as demonstrated by Mega Pinser, Flying/Fighting has fantastic Neutral coverage. My problem with this one and why i won't vote for it again is that we have seen what Fighting/Flying coverage does in the metagame. I like to vote for not so much the best theorymon, but the ones that would change how the mon plays in the meta game, or how much it shifts a metagame. This is pretty much a special mega pinser, and that doesn't really make me appealed to it. Plus Hurricanes confusion chance is disgusting.