The guinea pigs are 2015-introduced and cartoon-only pets. They belong Marisol Coxi, or at least her family. There's at least six of them, among which Gabi, Angelito, and Piggy Pantalones.
Though the guinea pigs look hostile and dangerous, they are actually very friendly. Piggy Pantalones enjoys hiding in people's hair.
Most of the guinea pigs are either green and white or purple and dark purple. At least one is hot pink with dark pink. All of the guinea pigs have tusks protruding from their lower jaws.
Marisol shows Abbey the guinea pigs during a tour through Monster Picchu. Abbey agrees they're adorable and incorporates them in her version of Marisol's video segments when her cousin leaves for Monster High.
- Presumably, Gabi and Angelito are the green and pink (a recolor of the purple one) guinea pigs on camera with Abbey.