#TrumpVsMusk

#TrumpAgainstMusk or #TrumpVsMusk (keeping the original format, which is common on social networks).

"Vs" is an abbreviation for "versus", which in English means "against". If you want to maintain the hashtag style, you can use:

#TrumpVsMusk (original format, more common online)

#TrumpAgainstMusk (translated version)