Reduces or cancels knockback taken from attacks. In a 1.8.8 PvP environment, this is devastating. A 0% velocity means you never move when hit. Servers often detect 0%, so cheats use 70-90% reduction.
The short answer:
Yes, some. Since Eaglercraft runs in a browser, any mobile browser (Safari, Chrome, Kiwi) can load a hacked client HTML file. However, performance is poor, and cheats like KillAura may not work well with touch controls. Eaglercraft Hacked Client 1.8.8
If you want to experiment ethically, set up your own (using the Node.js server files), and test cheat clients there without harming others. Reduces or cancels knockback taken from attacks