Yesterday I wrote about 'an event' for IELTS Speaking Part 2. Some of the expressions I used were informal:
- we chatted (talked)
- to get together with (meet)
- to catch up with (talk to someone you haven't seen for a while)
- what my friends had been up to (had been doing)
- to wind down (relax after something tiring)
The examiner would consider these phrases to be "less common vocabulary". In other words, a few phrasal verbs or informal expressions can help you to get a high score in IELTS Speaking.