Some examples of words that sound like "sh" are "sugar" and "sherbet." In the case of "tissue," the "ss" sound is pronounced differently than "sh" and does not have the same sound. "Pressure" also does not have the "sh" sound.
Some words with "ch" that sound like "sh" include "champagne," "chandelier," and "chaise."
In English, the letters "ci" typically sound like "sh" when followed by an "i" or an "e." This pronunciation is common in words like "ocean" or "special."
Mission, passion, pressure.
The "ch" makes a "sh" sound in words like chef or machine because it follows the rule of English pronunciation where "ch" can have a "sh" sound when it comes after an "e" or an "i." This pronunciation comes from the influence of French and other languages on English.
It is USUALLY pronounced as an s, but not always. There's the -cious words, where it has the sound 'sh': delicious precious specious meretricious etc. (not to mention 'licorice') Similarly, there the 'sh' sound for -cial words like facial and special. Also there are words that have been adopted from other languages but kept a trace of their original pronunciation: Celtic, for example. There are some other pronuniciations for ce, such as cello (pronounced 'chello'), cembalo (chembalo, with a 'k' sound). In the words foci and loci (acceptable plurals of focus and locus) the c is pronounced like a 'k'. The letter 'c' also makes the 'k' sound in the word 'arcing.'
Slant-sh (like slant with the additional "sh" sound)
Sure! Here are some words that contain the "sh" sound: Ship Shoes Fish Brush
Special Facial Racial
Conscience
the sh was represented by a horizontal rectangle, called a "garden pool" 
shush crush blush lash