What is known about Pokemon size with relation to IV's and stats?

Is there any info as to pros/cons of your pokemon's size?
(I have heard some say that XL or "Colossal" in the appraisal indicates stronger attacks, while XS or tiny pokemon have better chance to dodge or evade...)

Is there any known, or guessed at, future use or relevance for this descriptor? I never see it mentioned on any sites....