Huge ass ****ing list incoming. After some personal lab testing and combining stuff here it is. Some notes are messy as most (not all) were made by me so yeah hopefully you'll understand it. I'll edit the list as I add more to it.
Bowser
-Dash attack can be bowser Bombed.
-F tilt and up tilt can be Bowser Bombed.
-Dash attack can be Bowser Bombed.
Bowser jr
-F and up smash with drop kick.
-Dash attack can be Bowser Bombed (BE QUICK). You CANT Drop kick.
-F tilt and up tilt and be Bowser Bombed.
Charizard
Flare Blitz
- Dash, up-smash
Back-air - Beat it out with a DROPKICK
All smashes can be punished by drop kick on block.
All tilts and 3rd jab hit can be bowser bombed.
Dash attack can be Bowser Bombed and drop kicked
Captain Falcon
Falcon Fsmash and Knee are guaranteed fsmashes on shield.
F smash can be drop kicked on block. Down smash cannot it pushes back.
D tilt and up tilt can be Bowser Bombed.
Dash attack can be Bowser Bombed but not dropkicked
Falcon Kick can be Drop Kicked.
Dedede
Down smash, up smash drop kick.
Jab - Bowser Bomb in-between jab 2 and 3
All tilts -Bowser Bomb
Dash attack can be Bowser Bombed
Diddy
F tilt and up tilt can be bowser bombed.
Monkey Flip
- Run away, pivot grab/tilt
>smash can be punished with bowser bomb
down smash, both bowser bomb and drop kick.
Dash attack BOWSER BOMB WILL WHIFF. DROPKICK WONT WORK EITHER.
DK
-All tilts EXCEPT down tilt can be bowser bombed. Jab 1 can be bowser bombed if he doesn't go for jab 2. Jab 2 can be bowser bombed.
-Down smash can be punished with drop kick.
-Dash attack can be bowser bombed and dropkicked (might have to turn around)
Doc
-Dash attack cannot be dropkicked.
Dark
-Dash attack cannot be dropkicked
Duck Hunt
-All tilts can be bowser bombed with tight timing.
-F smash with drop kick.
-Dash attack can be Bowser Bombed and drop kicked
-His disco at up close can be Bowser Bombed.
Fox
-Up tilt Bowser Bomb.
-Drop kick for up and down smash
-Bowser bomb for his f smash.
->b for neutral air on block.
-Dash attack be dropkicked but it's tight timing.
Falco
-F and up tilt can be bowser bombed.
-Down and up smash can be drop kicked.
-Dash attack can be Bowser Bombed but not Drop KIcked.
Game and watch
-All tilts can be bowser bombed.
-Down smash is the only one punishable by something big...bowser bomb. Rest is nada.
- >smash and up smash cannot be punished by whirling fortress.
-Dash attack bowser bomb. DROPKICK WILL WHIFF.
-Judgement hammer usually can be Bowser Bombed.
Ganon
-Only down smash (front hit) can be drop kicked. Opt for something else.
-Bowser bomb will WHIFF on down tilt. Every other tilt can be bowser bombed.
-Dash attack can be Bowser Bombed. (Can't be dropkicked).
-Wizard Foot can be Bowser Bombed.
Greninja:
-F smash and down smash with dropkick. Up smash pushes back too much
-Shadow sneak with drop kick.
-F tilt can be bowser bombed
-Dash attack can be Bowser Bombed but not dropkicked.
Ike
-F tilt, down tilt and jab 3 can be bowser bombed.
Aether
- DROPKICK
Quick draw
- DROPKICK
Dash attack can be Bowser Bombed and Drop Kicked.
Jiggly
-Down smash drop kick. Everything else Bowser Bomb.
-All jabs and tilts are safe from bowser bomb.
-Dash attack can be Bowser Bombed and drop kicked.
Kirby:
-F tilt can be Bowser Bombed
-Dash attack can be bowser bombed but sometimes he'll end up behind you, be aware of this. He cannot be drop kicked.
->smash on block can be punished with raw >smash.
Kirby's down smash can be punished with bowser bomb. (f smash too slow)
Down air can only be punished by command grab.
Flying cutter can be Bowser Bombed close.
Link
-Up tilt can be Bowser Bombed.
-All smashes can be drop kicked.
-Dash attack can be drop kicked.
-Link's jab three can be drop kicked.
Luigi
Jab 3 - Bowser Bomb
All tilts can be Bowser Bombed
Up-smash - Bomb if close, f-tilt/d-tilt if further away
F-smash - Dash grab or f-tilt/d-tilt
D-smash - F-tilt
Cyclone
- DROPKICK or bomb
Dash attack - Bowser Bomb or dorp kick (tight timing)
Green Missile
- DROPKICK
Littlemac
Every tilt except down tilt can be bowser bombed.
Jab - Roll in-between jab 2 and 3, do stuff
F-tilt - F-tilt, d-tilt, Bomb
D-tilt - Jab
F-smash - Bomb, d-tilt, f-tilt
U-smash - Dash grab
D-smash - F-tilt, d-tilt, dash grab
Straight lunge
- DROPKIIIICK if fully charged, Bomb if otherwise
Jolt haymaker
- DROPKICK
Dash attack - Bomb (drop kick will whiff)
Lucario:
-Jab 3 and up tilt can be bowser bombed.
-All smashes are punishable by drop kick. Be QUICK with his >smash though it's tight timing. If you can't get it down, go for bowser bomb instead.
-Dash attack can be bowser bombed and drop kicked
-His force palm can be bowser bombed.
Lucina:
-All smashes can be drop kicked.
-Dash attack can be dropkicked.
Mario
-Jab 3 can be bowser bombed.
-F tilt and down tilt can be bowser bombed.
-Down smash be punished with bowser bomb.
->smash can't be punished with bowser bomb or drop kick.
-Up smash is the same thing, can't be punished with either.
-Cape can't be punished by Bowser Bomb whirling fortress will work.
-Dash attack can be bowser bombed and drop kicked (tight timing).
(Perfect Shield)
-Drop kick for >smash and Bowser Bomb.
-Up smash can be punished with Drop Kick.
-Cape can be punished by fire. So it'll work with Bowser Bomb.
Mewtwo
-F smash with Bowser Bomb.
-F tilt and up tilt can be Bowser Bombed.
-Dash attack can be Bowser Bombed but not dropkicked
-Confusion can be Bowser Bombed.
Metaknight
-Last hit of f tilt and up tilt can be bowser bombed.
-Only up smash can be punished by drop kick.
-And yes, drill also cannot be punished by drop kick on block.
-Drill cannot be punished by drop kick on block. Opt for Bowser Bomb.
-You can also DROPKICK the end of Meta Knight's neutral-b.
-Dash attack cannot be Bowser Bombed. The second hit will whiff. Also cannot be dropkicked.
Megaman
-ALL smashes can be punished with drop kick. YES EVEN A FULLY CHARGED SHOT.
-Dash attack can be dropkicked
Marth
-F tilt and up tilt can be bowser bombed.
-Down Smash can be Bowser Bombed
-Dash Attack can be Bowser Bombed and dropkicked.
Ness:
-Down smash and up smash can be punished with Bowser Bomb.
-Only f tilt can be Bowser Bombed
-Dash attack cannot be Bowser Bombed (it's pretty safe)
Olimar
-Down smash bowser bomb
-Up tilt and down tilt can be bowser bombed
-Dash attack cannot be dropkicked. It can be Bowser Bombed but the timing is very strict.
Pac
->Smash cannot be punished by drop kick.
-Down smash can be punished by drop kick and bowser bomb.
-Dash attack can be bowser bombed but it is very strict timing, also he'll sometimes go behind you during the attack...so yeah maybe you just wanna opt for another punish.
-All tilts can be bowser bombed
-Jab 3 can be bowser bombed
(Perfect Shield)
-All smashes is punishable by Drop Kick.
Peach
-Spot dodge her >b and then punish with a backwards dropkick.
-2nd jab, up tilt, f tilt can be bowser bombed.
-DOWN TILT CANNOT BE BOWSER BOMBED.
->smash and down smash can be punished with Bowser Bomb if close.
-Dash attack can be bowser bombed and dropkicked (tight timing).
(Perfect Shield)
-All smashes are punishable with drop kick.
Palutena
-All Smashes can be punished with Drop Kick.
-Down tilt and third hit of f tilt can be bowser bombed.
-Her projectile can't be Bowser Bombed, try something else.
-Dash attack can be dropkicked.
Pit:
-All Smashes can be dropkicked on block.
-All tilts can be bowser bombed.
-Bowser Bomb will WHIFF on Pit's >b. Do Drop Kick.
-Dropkick will whiff on dash attack.
Pikachu
-Skullbash on block.
-F and up tilt can be bowser bombed.
-All smashes can be dropkicked.
-Dash attack can be Bowser Bombed and Drop Kicked.
Rosalina
Dash attack - Bowser Bomb
Jab - Roll in-between jab 2 and 3, or DROPKICK the last hit of the rapid jab
F-smash - Bowser Bomb
D-smash - DROPKICK, Bomb
U-smash - Bomb
D-tilt - Bomb
F-tilt - F-tilt, d-tilt
Robin
All smashes can be drop kicked.
-Dash attack can be dropkicked.
F tilt and up tilt can be bowser bombed.
Jab - In-between jab 2 and 3 (or elwind jab rush), roll towards Robin, DROPKICK (or whatever else you want)
Arcfire
- If close enough, roll towards Robin on reaction then Bowser Bomb
ROB
-All smashes can be punished by drop kick.
-Up tilt and f tilt can be bowser bombed.
-Dash attack can be Bowser Bombed but not dropkicked.
Ryu
-His neutral air can be bowser bombed.
-All smash attacks can be drop kicked.
-Up tilt and f tilt can be bowser bombed.
-Dash attack can be bowserbombed and dropkicked.
Sonic
Down smash with drop kick
Homing attack
- Spotdodge, then DROPKICK / or run away, pivot grab/tilt
Dash attack - DROPKICK
-Jab 3 can be Bowser Bombed
-All tilts can be Bowser Bombed
Shulk
Backslash
- DROPKICK
Up and f smash can be dropkicked.
Third jab and all tilts can be Bowser Bombed.
Dash attack can be Bowser Bombed and dropkicked
Shiek
-Bowser bomb in between her f tilts
-Down and up smash with drop kick.
-Dash attack can be dropkicked.
Samus
-All smashes can be dropkicked. (tight timing on her up smash).
-All tilts can be bowser bombed (be quick on some).
-Dash attack cant be dropkicked.
Toon Link
-Drop kick both f smash and down smash on block. Dash grab for up smash.
-F tilt (BE QUICK) can be bowser bombed.
-Safe, even from a Jab after a blocked boomerang.
-Dash attack can't be dropkicked or bowser bombed.
(Perfect shield)
-Raw drop kick and Bowser Bomb on all smashes.
Villager
-Down smash can be punished with bowser bomb. Everything else is safe even from a jab...
-F tilt and up tilt can be bowser bombed.
-You can spot dodge his grab and drop kick
-You can drop kick his axe.
-Dash attack can be bowser bombed and dropkicked.
(Perfect Shield)
-Raw drop kick everything
Wario
-Jab, all tilts EXCEPT HIS DOWN TILT can be bowser bombed.
-All smashes can be punished with drop kick. Also Bowser bomb EXCEPT his >smash.
-BOWSER BOMB WILL WHIFF ON WARIO'S DASH ATTACK DO A DROP KICK.
WFT
-F tilt and up tilt can be Bowser Bombed.
-All smashes can be dropkicked
-Dash attack can be Bowser Bombed and dropkicked.
Yoshi
Up tilt can be bowser bombed.
Jab - After jab 2, jab him back (or you can side B, but, yeah...)
Dash attack - DROPKICK (timing is hard might have to turn around)
Down-air - Bowser Bomb (if you're crazy enough to shield the whole thing)
Zelda
-None of her smashes can be drop kicked. Pushes you too far for Bowser Bomb ;[ try up b.
-F and up tilt can be bowser bombed.
-Dash attack can be Dropkicked.
ZSS
-F smash with drop kick.
-Jab 2 and all tilts can be bowser bombed.
-Bowser Bomb will whiff on her dash attack.
-Dash attack can be drop kicked
Everyone
Ledge attack - Out-of-shield up-smash or Bowser Bomb (just don't kill yourself lol)