“To Become” and “To happen” are important for supporting verbs in English.
In Gujarati both “To Become” & “to happen” is થવું(thavuM)

It might sound confusing now but the context in which this verb is used will convey appropriate meaning.

Forms of this verb will be created as per gender and multiplicity of કર્તા (kartA) i.e. doer of the action. If કર્તા (kartA) unknown or abstract then it is assumed to be neuter singular and verb form is created accordingly.

What happened? :- શું થયું (shuM thayuM)
What will happen? :- શું થશે (shuM thashe)
What is happening? :- શું થઈ રહ્યું છે (shuM thaI rahyuM Che)
It did not happen:- એ થયું નથી (e thayuM nathI)
I will become teacher:- હું શિક્ષક થઈશ (huM shikShak thaIsh )
You(boy) became pilot:- તું પાયલટ થયો (tuM pAyalaT thayo )

When you want to use such sentences for adjectives, in English, we generally use forms of “To be” instead of “To become”. But in Gujarati, you can use થવું(thavuM)

I will be winner:- હું વિજેતા થઈશ (huM vijetA thaIsh)
She(polite) will be happy:- તેઓ ખુશ થશે (teo khush thashe)
He was mad:- એ ગાંડો થયો (e gAMDo thayo)
They(a group of boys) were mad:- તેઓ ગાંડા થયા (teo gAMDAM thayAM)
She(polite) was mad:- તેઓ ગાંડાં થયાં (teo gAMDAM thayAM)
She was happy:- તે ખુશ થઈ (te khush thaI)