Mynd, Gwneud, Dod, and Cael all have irregular forms in their concise constructions. List below

Irregular Forms Table
Mynd (to go) Gwneud (to do, make) Dod (to come) Cael (to get)
Past Tense Concise
Fy Es i Gwnes i Des i Ces i
Ti Est i Gwnest i Dest i Cest i
Person Aeth person Gwnaeth person Daeth person Cafodd person
Ni Aethon ni Gwnaethon ni Daethon ni Cawson ni
Chi Aethoch chi Gwnaethoch chi Daethoch chi Cawsoch chi
Nhw Aethon nhw Gwnaethon nhw Daethon nhw Cawson nhw
Future Tense Concise
Fy a i na i do i ca i
Ti ei di nei di doi di cei di
Person eith person neith person/naiff person daw person ceith person
Ni awn ni nawn ni/newn ni down ni cawn ni
Chi ewch chi newch chi dewch chi cewch chi
Nhw ân nhw nân nhw dôn nhw cân nhw