I was battling a passer-by when I was down to my last Pokemon, Greninja.I am sure that it was not choice scarf because at the start of battle, I led with Gengar and it outspeed the Krookodile and landed the Hypnosis before I used Substitute.
The base speed of a Gengar is 110, Greninja speed is 122 and Krookodile is 92.Why is that so?
There's multiple possibilities on how this happened.
-The Krookodile didn't try to use Substitute and was actually Scarfed. Is your Gengar scarfed?
-Your Opponent laid down Sticky Web, slowing your Greninja down or somehow lowered it's speed. You may have missed it.
-The Krookodile had extra speed Baton Passed onto it or used some sort of buff move.
-Your Greninja had an Iron Ball or Lagging Tail tricked onto it.
-Greninja was Paralyzed, lowering it's speed.
-Glitches and hacks are a thing.
Well base stats don't decide everything. Your Gengar could've been faster than your Greninja if it had higher IVs, EVs and a speed boosting nature. If so, then your Gengar out sped it, and your Greninja was just very slow, or Krookodile was Choice Scarfed, or your Greninjas speed got lowered. I think it's most likely its speed got lowered.
I hope I answered your question!