The Tuss,Dave Monolith, Acid Vocals style etc.

How do i make that typical "robotic" vocal effect ? is it just a vocoder effect ?

Give some examples.

yes

As far as I can tell, on the more recent Aphex tracks, it's a voice speaking, vocoded with a synth playing a chord, and usually pretty buried in the mix. You could achieve a more realistic choir/chorus effect by vocoding monophonically and multitracking it, layering up each note of the chord separately, each with a different take of the vocal. Whether you'd rather do that or not depends on your particular style and the particular tracks you're working on, of course.

Do you mean those vocalish acid basslines ? If so, you can achieve such results by using multiple filters in a row on your synths.

Well, if you want something to sound vaguely like it has vocal resonance, you could do with a few bandpass filters in parallel (not serial) set to vocal frequencies...

Don't forget formant filters too! That's their whole job :)

What about this kind of vocal effects -

Poly synth into vocoder.