Two-Five-One progression with altered V7 chord (IIm7 - V7alt - Imaj7)
In the first lesson about the two-five-one progression wie only used natural tensions 9, 11and 13. But whenever a V7 chord resolves to a I chord, we can add altered tensions to the V7 chord. That often sounds more "rich" or "jazzy", however your ear has to make the decision between natural or altered (or mixed) tensions.
Natural and altered tensions within one bar
It's a very common thing to play a V7 chord with natural tensions (also V7sus) in the first half of the bar, then a variant with altered tensions. Altered tensions and natural tensions can also be mixed, e.g. G7(b9,13).
Which tensions for sus chords?
Indeed a b9 is possible in sus chords (b13 is not very nice in a sus chord; sus with #9 doesn't exist, because this results in a minor chord with an 11). But a V7sus(b9) chord has the tendency to resolve directly to the I chord and therefore has the tendency to completely replace the V7 chord. A sus(b9) chord goes nicely with e.g. IVmaj7 V7sus(b9) Imaj7. Just try!