Aerodactyl legend: Well, that's on my ghetto Bellossom since I now have a good Bellossom with a hidden power 70. Hyper Beam looks like a bad idea on paper, but the Bellossom actually KO'd a full hp OU poke with it. When I think about it, bp 150 is stronger than even a super effective hidden power at 70{140}, and with her speed under sunny day, she at least hits first before they knock her out. Hyper Beam is more like her last attempt after she's set up sunny day on the modest version.
And Excadrill can't KO a Bellossom that's invested even a little in defenses, my bold Bellossom survived an X-scissor, stun spore'd the Excadrill and was able to go first the next turn. The same holds true against Tyranitar. None of Tyranitar's attacks are able to KO Bellossom, even if it goes first, the next turn it will always go last due to Sunny Day or Stun Spore, thus, allowing Bellossom to moonlight on the next turn and she's able to stall Tyranitar afterwards even if it uses Crunch. Even a Bellossom that has had little investment in speed will still outspeed Tyranitar under Sunny Day{and obviously if its been stun spore'd.}
Bellossom truly has been overlooked. She is an incredible anti-sandstorm poke. Many Excadrill have faultered thinking that she was an easy KO, only to find themeselves paralyzed/under sunny day weather and being forced to switch out/stay in and be KO'd. The best part about stun spore is that almost nothing in the game resists. Bellossom really messes up teams, especially the bold version. Only the modest version has failed a few times, but she is ghetto cause she doesn't have stun spore. The bold, stun spore version is where it's at. Sporing anything that resists Solar beam has proven to be a great strategy.
To reduce confusion, I will post the builds seperately.
bellAWESOMEST {The version that's able to compete in the OU tier on PO.}
@Zoom lens
Bold
Bold: 252 hp/252 df
Solar Beam
Stun spore
Moonlight
Sunny Day
Ghetto Bellossom {My in-game Bellossom which couldn't be bold and has wild IVs, so I gave her a more offensive moveset and she is still tearing things up like out speeding and taking out a fully EV trained HAXORUS with out stun spore while under the sun. Surviving non-stab super effective attacks on random matchup, etc.}
@Heat rock
Modest
Modest: 100 hp/ 255 spatt/ 155 spd
Solar Beam
Hyper Beam
Moonlight
Sunny Day
Either version: If she manages to set up Sunny Day{and she will if the opponent doesn't have a stab, super effective attack} she will bound back with moonlight if she survives the next turn, or if damage is less than 50%, she will stun spore them if they don't carry taunt or are about to switch out. If they take neutral from Solar Beam and are slower than her after sunny day, she will strike with that instead. The purpose of Zoom Lens is to paralyze something when sunny day isn't up and she only has 1 turn to do something of importance before being 2 HKO'd by something. Under the sun, She is able to check things like Gyarados, Politoed, Tyranitar, Gliscor{2HKO with Solarbeam}, Swampert{OHKO}, Starmie, Landorus{2HKO} and tons of others. Her counters are any fire types like Chandelure, who can OHKO her with Fire Blast and go first if sunny day isn't up. If it is, she will attempt to stun spore anything she outspeeds before being KO'd by a sunny day boosted fire attack. If hax takes effect and the fire poke is paralyzed that turn, she is able to switch out without being burned. I would say steel types, but she can just stun spore them and switch out without taking much damage from them.
A good OU partner for her is Jellicent, who will resist all attacks that bellossom is weak to {bug, fire}, as well as Bellossom being able to resist attacks that Jellicents is neutral or weak to{ground, electric, grass,}. Moonlight under the sun, which she can manipulate and set up against perma weatherers, allows her incredible recovery, being able to regain a huge amount. However, the only drawback is that it will reduce the effectiveness of Jellicent's water type attacks, although in the mean time, she can just stall out till sunny day runs out.