for a good reverb, download SiR, its a fantastic impulse based reverb plug, and its freeware. but i dont know what kind of reverb it is youre looking for when you say like dubstep, do you have a snippet or something?
for sub i use the 3xOsc..... turn down oscs 2 & 3 and just use osc 1... set it to sine wave, and raise the root note by a few octaves in the channel settings
copy & paste your melody to the 3xOsc
its a good idea to high pass the sound your adding bass to.... send it to an fx track, add a "fruity parametric eq 2" use the 40Hz cut preset, and adjust the frequency
as for reverb.......
well i dont make much dubstep but i do make a shit load of dub, so i guess there are similarities
for snares its all about BIG reverbs, the reeverb 2 in FL is pretty good, turn up the wet amount and play with the decay and size amounts..... also tweak the high and low cuts
if you wanna get really dubby with the track, its all about a combination of delays and spring reverbs
most delays are good for dubbing, i use kjaerhaus audio's classic delay, audiodamage's dubstation and soundfonts.it's tape echo alot.
a good setting for a standard constant dub delay, is a good amount of feedback, with the delay line fairly narrow so adjust the high and low cuts to kind of bandpass the delayed signal
for a "every now and then" delay (as im gonna call it) where a delay only effects a sound every now and then but seems to delay for ever, its all about riding the feedback.... as it starts to decay out, whack it up and then drop it and keep doing it...... it can be hard but can sound sick if you get it right...... automation clips help with this, zoom in to make precise adjustments
right, spring reverb....
there are no really good spring reverb vst's, theres PSP's spring verb which is ok on instrument parts, but the closest ive got to a proper full on king tubby style "squishy echo" is by using Altiverb (which is a convolution reverb) with a spring reverb impulse response (tis a really good IR, i'll upload it if anyone is interested)..... the problem with convolution reverbs are that they are SOOOO cpu heavy its unreal, i cant even run altiverb for long before my cpu freezes up completly
you can get real spring reverbs for not too much... got my eye on a spring king atm, check it.....