Formal:
* Bardzo szczęśliwy/szczęśliwa (bardzo - very, szczęśliwy/szczęśliwa - happy) - This is the most literal and formal translation.
* Radosny/radosna (radosny/radosna - joyful, happy) - This is slightly less formal than "szczęśliwy/szczęśliwa" but still polite.
Informal:
* Bardzo wesoły/wesoła (bardzo - very, wesoły/wesoła - cheerful, happy) - This is a more casual and informal way to say "very happy."
* Super szczęśliwy/szczęśliwa (super - super, szczęśliwy/szczęśliwa - happy) - This is a very informal way to say "very happy," often used among friends and family.
Other options:
* Przez szczęśliwy/szczęśliwa (przez - extremely, szczęśliwy/szczęśliwa - happy) - This means "extremely happy" and is very strong.
* Z radosny/radosna (z - with, radosny/radosna - joyful, happy) - This translates to "with joy" and expresses a state of happiness.
Remember to choose the appropriate phrase depending on the situation and your relationship with the person you are talking to.