I use both bitmap images and vector drawings in Moho to create animations for our television productions. Oftentimes, I'll mix both types of art in a single character.
For examples of bitmap rigs, see The Croods, and All Hail King Julien on Netflix. Check out the Interactive Episode of Puss-In-Boots for an example of a hybrid rig. While working on Boss Baby, I used vector drawing almost exclusively in our rigs. The type of art I used was determined by the designs and animation style required by the TV show. (You can see some of this in my three most recent demo reels here:
https://vimeo.com/channels/littlegreendog.)
For bitmap art, you'll want to use an external program that supports Layered PSD because Moho does not have bitmap tools. (Well, 13.0 briefly supported bitmap painting, but it didn't work very well and was removed in 13.5.5 when Lost Marble took over development.) Since version 13.5.5, Moho has gotten very smart about keeping track of layers, so you can change the art in the PSD, and it will update in Moho.
Back in Moho 12.5, I preferred to use PNG files, exported from Photoshop using the free
Export Layers To Files Fast script. This tool batch exports layers to separate files, and has a ton of options not available with Photoshop's native exporter. But if you have Moho 14, it's practically unnecessary to use PNG files.
When using bitmap art, Moho has multiple advanced tools for deforming the artwork. As mentioned, you can seamlessly combine them with vector art too because you can fill and stroke vector art with bitmap elements. (Like in my Puss example.)
For vector art, I almost always use Moho's tools. Moho's vector tools are very good, especially in Moho 14. For art that needs to be precisely deformed using bones, you'll want to use Add Point, which got a nice upgrade in Moho 14. I used Add Point to create all of my Boss Baby rigs, and they animated perfectly!
If you use an earlier version of Moho, be sure to get Mult Rush's
MR_Curve tool. (This tool was just updated to work in Moho 14 too!) You'll also want to get Hayasidist's HS_Shape tool...this is an advanced variation of the native Shape tool.
If want to use an external vector program with Moho, version 14 can import SVG and preserve most standard features of drawings. For Moho 13.5.5 and 12.5, be sure to use SimplSam's
SS_SVG Import script. I used this for a lot of elements when I was the Lead Digital Animator on
Fast & Furious: Spy Racers.
Re: Freehand and Blob Brush, these tools are Moho's freehand vector tools, and they work quite well in Moho 14. They can work okay in Moho 13.5.5 and earlier, but if you use a tablet, you need to make sure the
Use Pen As Mouse option is disabled in Windows Pen And Ink control panel. (Disabling this is unnecessary for Moho 14...it just works!)
IMO, these tools are good for drawing elements that won't be deformed with bones and any items that you want to quickly draw for a
Switch layer (faces, hand poses) or the
Frame By Frame layer. They're less suited for bones because you usually want to carefully place your points to get the best deformation quality. That doesn't mean you can't use Freehand this way; it's just better to use Add Points if precision and getting nice definitions is critical.
Hope this helps.