Plurilingualism is an inclusive language teaching approach to sustain multilingual societies, but there is little investigation on teacher candidates' (TCs) beliefs and challenges before and after its implementation. This interpretive qualitative study introduced plurilingualism in teacher education at a Canadian university. Sixteen TCs participated in the study, which 1) investigated TCs' conceptualizations of plurilingualism, and 2) examined TCs' perceptions of overall affordances of critical plurilingual pedagogies before and after their practicum. For four months, participants experimented with plurilingual pedagogies such as translanguaging and cross-linguistic analysis, designed tasks, and taught lessons. Five types of data were generated: 1) weekly annotations of readings on Perusall, 2) designed language tasks, 3) task delivery demonstrations, 4) lesson plans, and 5) final reflection after the teaching practicum. Inductive content analysis was conducted on NVivo with data triangulation. Findings suggest that TCs shifted their views of language, and aligned plurilingual pedagogies with equity, diversity, inclusion and decoloniality principles. Findings also show that TCs transgressed the monolingual discourses often present in schools, and felt empowered after the training. We call for the inclusion of critical plurilingual practices in teacher education programs for the sustainability of multi/plurilingualism.