Gwilym oedd y band cyntaf i Côsh arwyddo er mwyn datblygu'r label ac hynny wedi iddynt ryddhau 2 gân yn unig ar Soundcloud. Roedd 'Llechan Lân' a 'Llyfr Gwag' yn ganeuon amrwd, ond roedd digon yna i argyhoeddi fod ganddynt botensial mawr. Llai na blwyddyn wedi iddynt rhyddhau eu sengl gyntaf efo Côsh, roedd yr albym 'Sugno Gola' yn cael eu rhyddhau yn cynnwys caneuon fel 'Catalunya' ac 'Cwîn', sydd wedi'u hoelio fel band mwyaf poblogaidd Cymru ymysg pobl ifanc. 

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Gwilym were the first band Côsh actively recruited to develop the label, after releasing only 2 songs on Soundcloud. Although 'Llechan Lân' and 'Llyfr Gwag' were raw, there was enough about them to suggest that they had huge potential. Less than a year after they released their first single with Côsh, their debut album 'Sugno Gola' landed, including songs like 'Cwîn' and 'Catalunya' which would cement their place as Wales' most popular band among young people.