Having had to look this up more than once -- and always finding it rather incomplete here is the most current full list of Sidekick Abilities -- if I missed any please let me know -- as i find it rather frustrating that they can not be viewed easily. Note the descriptions are not 100% accurate (aka word for word) however the meanings should be the same. Only re-worded either for consistency and/or clarity.
1st Tier
Black Ice : You have a 30% chance to stun your opponent for one round. Can only happen once per fight.
Comeback Starter : You have a 60% chance of dealing another strike after being hit by your opponent critically. Can happen multiple times in a fight.
Constant Dripping : You have a 40% chance of dealing damage equal to 50% of the triggering hit over 4 rounds. Can happen multiple times in a fight.
Constant Slimy Dripping : You have a 40% chance of dealing damage equal to 50% of the triggering hit over 4 rounds. Can happen multiple times in a fight.
Flipper Smash : You have a 50% chance that your Critical Hits will deal out 80% more damage. Can happen multiple times in a fight.
Head Butt : You have a 20% chance to stun your opponent for one round. Can only happen once per fight.
Horribly Glib : You have a 60% chance of dealing another strike after being hit by your opponent critically. Can happen multiple times in a fight.
Intercepted : You have a 15% chance to reduce your opponent's Missile damage by 75%. Can happen multiple times in a fight.
Me First : Increases the probability of dealing out the first strike by 40%
Not Like This : You have a 45% chance of dealing another strike after being hit by your opponent critically. Can only happen once per fight.
Not So Bad : You have a 20% chance to reduce opponent's damage dealt by 40%. Can only happen once per fight.
Rainbow Glitter Powder : You have a 40% chance to incapacitate your opponent for one round. Can only happen once per fight.
Razor Sharp Teeth : You have a 40% chance of dealing damage equal to 50% of the triggering hit over 4 rounds. Can happen multiple times in a fight.
Sharp Beak : You have a 50% chance that your Critical Hits will deal out 80% more damage. Can happen multiple times in a fight.
Sharp Scissors : You have a 50% chance that your Critical Hits will deal out 80% more damage. Can happen multiple times in a fight.
Spike Burst : You have a 40% chance of dealing damage equal to 50% of the triggering hit over 4 rounds. Can happen multiple times in a fight.
Steady Ink Drops : You have a 40% chance of dealing damage equal to 50% of the triggering hit over 4 rounds. Can happen multiple times in a fight.
Swift Fin : You have a 30% chance to stun your opponent for one round. Can only happen once per fight.
Thick Hide : You have a 25% chance to reduce your opponent's Missile damage by 80%. Can happen multiple times in a fight.
2nd Tier
Body Guard : Critical Hit chance of opponent reduced by 5%
Catch the Ball : Increases your Missile damage by 20%
Cockered Up : Your guild trophy minus points are reduced by 15%
Eagle Eye : Dodge chance of opponent reduced by 5%
Four Eyes : Increases your Base Intuition by 10%
Get the Stick : Increase Missile Damage by 10%
Hard Shell : Decreases your opponent's Critical Hit chance by 6%
Jogging Partner : Increases your Base Stamina by 10%
Penalty Taker : Decreases your opponent's Dodge chance by 6%
Protective Spikes : Decreases your opponent's Dodge chance by 6%
Smart Guy : Increases your Base Intelligence by 10%
The Strength of Two : Increases your Base Strength by 10%
3rd Tier
Allergic Reaction : You have a 15% chance to attack twice in a row. Can happen multiple times in a fight.
Bone Cracker : Your Critical Hits have a 70% chance to stun your opponent for one round. Can happen multiple times in a fight.
Bulls Eye : You have a 30% chance to deal 50% extra critical damage. Can only happen once per fight.
Cheating Death : When your opponent actually deals out a winning strike, your hit points are set to 1 instead. Can only happen once per fight.
Hakuna Matata : When your opponent actually deals out a winning strike, your hit points are set to 1 instead and your next attack will cause 50% more damage. Can only happen once per fight.
No Stress : You have a 50% chance to prevent your opponents first attack. Can only happen once per fight.
Protective Shield : You have a 25% chance to Dodge an actual hit. Can only happen once per fight.
Revenge! : You have a 30% chance to throw back 50% of the received damage of a critical hit immediately. Can only happen once per fight.
Shark Bait : You have a 15% chance to land a second Critical Hit after a successful attack. Can happen multiple times in a fight.
Sharp Claws : You have a 40% chance to deal 50% extra critical damage. Can only happen once per fight.
Snow Avalanche : You have a 15% chance to attack twice in a row. Can happen multiple times in a fight.
Take Cover : You have a 20% chance to Dodge an actual hit. Can only happen once per fight.
Tit for Tat : You have a 15% chance to throw back 25% of the received damage of a hit immediately. Can happen multiple times in a fight.
Two Are Better Than One : You have a 25% chance to attack twice in a row. Can only happen once per fight.
Well Padded : You have a 10% chance to reduce your opponents damage by 25%. Can happen multiple times in a fight.
Note : It has come to my attention that Horribly Glib is potentially THE most broken ability in the game (but perhaps I am wrong). However from what I can see it is THE ONLY ability where the character benefits significantly by completely tanking one of their attributes. All the other abilities do not seem to benefit in such a way (can anyone point out another ability that does something similar with any other attributes). For basically with this ability the player can minimize their Brain attribute which then turns into an advantage in combat allowing them to then add all all those freed up points to their other 3 attributes. Again I could be wrong but I do not think you can do this kind of thing with any other ability and yes being able to ignore one fourth of your attributes can be a very big advantage. That is unless everyone is doing it -- which will eventually be the case as more folks realize just how decidedly lopsided it makes things. Now I would be delighted to hear any solid rebuttals of this if anyone can point out how it is not that big of an advantage under the current framework (aka not everyone is using it kind of thing).