Illustrator type brushes ?? The key one for this is the brushes panel. Create some characters on the art board, anything, perhaps a word or just a single character or a whole paragraph or page. Drag that design from the art board to the panel.
As soon as you add any characters to the panel, you will be prompted to set it as a pattern etc, select one of the available options, you will notice that some options are not available for use with the characters. You will then see a dialog with a number of options depending on the choice made such as size, spacing, scatter, rotation etc and you can have then set to a fixed value or random or pressure etc (depending on art pad etc) and you can set a range for them such as a minimum and maximum setting. The minimum and maximum pops up if you select random. If you choose say the art then you will see an error and before you can continue you will need to expand the characters or word etc via the object menu and expand. You will then be able to enter a width setting which can be fixed as well as random etc and you can scale proportionally, stretch and stretch between guides etc. You can also set the direction and the end result does radically depend on the direction such as bottom to top or using left to right, this with words can make quite a difference to the design created.
You can set colorization for the design you have created. If you want to use this, I would suggest some earlier setup is required such as have the characters set to a certain color such as red or green and not black (tricky to tint that). The range of options for the color manipulation is limited to tints, tints and shades and hue shift. Again, creating a design with colors beforehand will help here.
With the stroke applied via the paintbrush tool or using a shape and adding it to the stroke, you can always, with it selected, double click the entry in the panel and change the settings for the stroke. If you make any change such as reducing or increasing the guides you and click OK to save the preset, a dialog will pop up saying do you want to leave the stroke as was or if you want to apply it to the stroke.
You can set the guides to include the entire set of characters but you can also set the guides interactively during the edit phase to include only one or two characters in between the guides. Those characters are stretched as you draw your design or apply to a shape, the characters outside of the guides are not stretched and you will see them more clearly that the inner design. Say you have a set of characters 'abcd' and you have the guides covering the 'bc' then that will be stretched as you apply the type brush but the 'a' and 'd' will still be clearly visible and not stretched.
You can also rasterise the design via the object menu and rasterise command and you can then use the design as an image and not a vector and you can add other effects to the design such as standard raster effects (blur etc) and use that as a stroke preset. You may wish to do this if you have some words or characters that have styles applied as you will need to rasterise them via the object menu before saving the preset to the panel.