Mobile Image Grid
Galleries using an image grid for smart phones should be restricted to a maximum of about 12 images. The EverWeb image gallery widget doesn't play too well on mobile devices due to the small size of the enlarged image. It also isn't capable of providing captions.
Shadowbox is a much better option since the popup image can be adjusted to fill the viewport and captions can be added in the Title attribute of each image link and there are other possibilities...
PhotoSwipe was designed specifically for mobile devices but has the unusual feature of being swipeable on conventional websites using the mouse.
The popup slideshow has play, back, forward and close buttons. The captions are derived from the alt attribute in the thumbnail img tag.
Swipe Gallery Widget
There is a widget which launches a PhotoSwipe style slideshow from a single thumbnail image - Swipe Gallery with Captions.
Several of these can be used on one page so that a large number of images can be display on one page using very little space.
Lightbox Image Widget
In some respects it is a better idea to launch single images from a thumbnail grid rather than a slider. In this case either of the Lightbox Widgets will get the job done. This has the advantage of allowing both the thumbnail and the expanded images to have a caption and the ability to add Alt text for SEO.