Fox (SSBM)/Up throw
Fox throws the opponent up into the air, then shoots them with his Blaster. This throw can easily combo into an up aerial on virtually every character in the game, a combo which can KO characters with low or close to low falling speeds at percentages as low as 65%, especially on stages with lower ceilings such as Yoshi's Story or Pokémon Stadium. This combo can also be used on virtually every other character in the game at higher percentages. The move can also combo into an up tilt or up smash, especially against fastfallers; the latter is a KO option against fastfallers at percentages just above 100%. The throw can also chaingrab fastfallers to some extent (from around 10% to 40%), and it can lead straight into an up tilt, up smash, or up aerial at percentages starting with around 45%.
Chaingrab on fastfallers
Against Fox, up throw can chain into itself regardless of DI from 0-66% damage if the thrown character has a lower port number and from 0-54% damage if the thrown character has a higher port number than his opponent (both before unstale throw). If Fox has more damage and holds left or right, chaingrabbing is possible until 86%.
Against Falco, up throw can chain into itself regardless of DI from 0-81% damage if the thrown character has a lower port number and from 0-66% damage if the thrown character has a higher port number than his opponent (both before unstale throw). If Falco has more damage and holds left or right, chaingrabbing is possible until 103%.
For both of these, pivot or DD-JC (dash dance jump cancel) grabs are required during quite many percent ranges. The timing is somewhat lenient, though; most of the time, there are one or two frames of leniency.
Additionally, finishing with up smash is possible as well. The highest percentage this can still be done for no DI is 102 if the thrown Fox has the higher port number and 109 if the thrown Fox has the lower port number.
For both of these, executing it correctly (dash for 4-5 frames, pivot, charge up smash) makes it possible to get a guaranteed kill on any stage (even Dream Land N64) unless platforms interfere.
The speed of this throw depends on the opponent's weight.