Dwarf galaxies are the most common type of galaxy in the Universe and have emerged as powerful testbeds for our standard cosmological model LambdaCDM on small scales, where several tensions persist. This thesis focuses specifically on the phase-space distribution of dwarf satellites around massive hosts. Several nearby hosts, including the Milky Way, appear to have flattened, kinematically correlated satellite configurations that are uncommon among LambdaCDM analogs---the planes-of-satellites challenge. Robust tests require large, contamination-controlled satellite samples across diverse environments, which are challenging to obtain beyond the Local Group because dwarfs are intrinsically faint and generally have low surface brightness. This thesis contributes to the extension of phase-space studies beyond the Local Group by (i) evaluating and refining methods to quantify phase-space distributions, in particular lopsided satellite distributions and planes-of-satellites, and conducting statistical tests on such distributions in existing survey data (e.g., MATLAS, ELVES); (ii) expanding line-of-sight velocity coverage via VLT/MUSE spectroscopy of MATLAS candidates and establishing host membership; and (iii) developing an automated pipeline, combining classical methods with deep learning, to build a survey-scale catalog of dwarf galaxy candidates in the wide-field UNIONS survey. Across 68 host systems in MATLAS/ELVES, ~21% show significant lopsidedness with the signal strongest at larger projected radii, consistent with recent accretions and in line with LambdaCDM expectations. Follow-up on reported candidate planes generally revealed no significant tension with LambdaCDM when revisited with new data. An exception to this trend is the NGC 4490 group, where such a highly correlated structure was identified as uncommon in simulated analogs. In the MUSE program, we confirmed 75% of the MATLAS dwarfs in the sample as satellites; non-members tend to be late-types, supporting morphology as a membership prior. Our pipeline yielded dwarf probability scores for 1.5 million selected objects, producing the Galaxies OBserved as Low-luminosity Identified Nebulae (GOBLIN) catalog. GOBLIN contains ~43,000 high probability (>=0.8) dwarf candidates, which represents a significant increase in the number of high-confidence candidates in the local Universe. Taken together, the majority of our investigations into phase-space distributions of dwarfs revealed consistency with LambdaCDM given current data. There are, however, noteworthy exceptions, and several systems are still far from complete in terms of distance and velocity estimates. Such measurements are necessary to draw definitive conclusions. Our publicly available GOBLIN catalog contains a large sample of high-probability dwarf candidates, laying the foundation for targeted follow-up campaigns and future phase-space studies.