So far as the question of super floaty characters and super heavy characters, the data in the "U-throw Combos" section of my Snake MU Data Spreadsheet should answer which characters are way too floaty to combo off of throws. I say this based on my experiences playing Sheik as well as my comprehensive sense of Snake's throw to ascertain the similarities between a poorly DI'd Sheik down/back throw and Snake's up throw. Most of the followups seem relatively similar until higher percentages where Snake's launches much higher than Sheik's (I reckon it's a matter of Knockback Growth). I can link this data specifically if you wish, but it's easier to just say that the super-floaty, don't-even-hope-to-combo characters would be:
Jigglypuff, Kirby, Mewtwo, Peach, Zelda, Ice Climbers, ROB, Samus, Ivysaur, Luigi, Mario, Squirtle, Ness, and Olimar. This is roughly ordered by how positive I am of their difficulty as well. These are all characters who cannot be regrabbed by Snake past 10% (i.e. after 1 throw). You might add Dedede to this list depending on how much weight dependency matters with these throws, although I don't recall having much trouble comboing Dedede with Sheik. idk.
Conversely, super heavy (i.e. fastfalling) characters are:
Fox, Falco, Wolf, Falcon, Roy, Zero Suit Samus, Diddy Kong, Lucas, and maybe Sheik/Link/Ganon. This is a bit harder to decide where to draw the line since the lower ends of the spectrum (ZSS, Diddy, Lucas...) are all relatively close to the same combo weight as mid weight characters, but are distinctly more susceptible to followups for Snake at higher percentages.
As for which DI you should match each throw to, Down Throw beats DI in and Back Throw beats DI out. So say you grab someone facing to the right. If you expect them to DI to the right, you would back throw since that would be DI away from Sheik. Conversely, if you expect them to DI to the left, you would down throw since that would be DI into Sheik.
I don't know how much Up Throw has changed (if at all) in Project M, but it's primarily a niche mixup tool on fastfallers in Melee. On low-lying platforms, you could use it to mindgame them to DI onto the platform to escape and then tech read with DACUS or you can follow up with an aerial or a waveland into a launcher or grab, or if they DI into the center, I tend to f-tilt or u-tilt them into an aerial. That's the primary application I utilize U-Throw for in Melee and have some pretty solid success with it when I'm playing well.
Followups out of throws include:
- Dash attack (correct DI)
- Boost grab (correct DI in situations)#
- Techchase (any DI, but particularly correct DI)
- Dash -> tilts (Dash, press Down to cancel your dash state, then perform your tilt)
- any tilt (bad DIs)^
- jab (bad DIs)^
- Down Smash (bad DIs)
- WD -> normal (tilt/jab) or down smash (neutral DIs)
- JC/standing/Pivot grab (bad DIs)
- Up Smash (either DACUS or JC) (bad DIs)
- SH aerial (bair/fair/nair) (bad DIs)
#you can also pivot boost grab to throw off their DI intuitions even more since it's based on which way Sheik is facing to some degree and they may react to the throw before they react to your direction.
^these are all mixups to force a regrab
You can do basically anything off of bad DI honestly. Getting regrabs is mostly about reacting to their DI and/or positioning yourself to techchase (i.e. wavedash or foxtrot toward them).
