Assume I have Sticky Web up and a Clawitzer with a Mild nature and 252 Speed IVs. What speed tier (or notable things in particular) can Clawitzer outspeed?
Assume the same scenario, except Clawitzer has no Speed IVs. What can Clawitzer outspeed now?
A Clawitzer with no speed IVs and max speed EVs will have 194 speed. This is able to outspeed everything that has a base speed of 78 and below, assuming they do not invest at all in speed, regardless of sticky web.
With sticky web up everything that has a speed stat of 293 or below will be outsped by above Clawitzer when hit by sticky web (293 times 0.66 (or -1 speed stage) = 193.38 which when rounded down becomes 193). (someone correct me if this is rounded up.)
So with the above facts, everything with a neutral speed nature and full investement in speed (252Evs) with a base 97 speed stat (or less) will be outsped by your clawitzer.
However, if your opponent is running a +speed nature AND running full investment, then only pokemon with lower than base 84 speed will be outsped by your clawitzer with sticky web in play.
I know I have only given you number and base speeds, but I hope this is ok for you to work with.
Edit: I forgot to do with full Ivs, and the guy above me has done a much better job -.- Sorry.