need advice on the use of prepositions, thanks teacher

[Help Wanted]

Dear teachers,

Q1
Should I use "with" or "against" in the following sentence?

The girls are playing badmintons (with or against) each other.

Q2
The badminton players are practising badminton with each other.
(Anything wrong with this sentence? Please advice, thanks)

Q3
Which one is better in expressing gift exchanges?

Helen and her sister give each other presents at Christmas.
OR
Helen and her sister give presents to each other at Christmas.

Thanks soooo much, teachers

[Tdol]

When it's competitive, I'd use 'against', but with the practice, I'd use 'with'. With your sentence with 'presents', they both sound fine to me as a British English speaker, but I don't know if Americans would see it differently.

[Help Wanted]

Thank you sooooo much for your advice, teacher Tdol!

[Tdol]

You're welcome.