In general you don’t need more requirements to participate in an Erasmus Plus project, a exception of the country of residence and the age.
Anaway here you have some questions answered in advance:

1. Do I need a great level of english? For a Youth Exchange you don’t need a good level of english unless you’re a group leader or a facilitator, which in that case, you should be at least able to communicate. 
For a Training Course it is more recommended to have a better level of english so you can understand the course and express yourself better.

2. Can I participate if I have fewer opportunities (economical, disabilities, geographical, social, etc.)? Yes, the Programme seeks to promote equal opportunities and access, inclusion, diversity and fairness across all its actions. 

3. What else do I need? You need need motivation to participate, learn and share with other cultures!