I can't get arcade cannon as a companian because i need a speech skill of 75 is this the only way to get Arcade cannon?

I think you just answered your own question?

you can usually find skill books in the newspaper vending machines on the strip where the tops is...if you dont get the one you want reload and try again. ALSO, confirmed bachelor perk lets you skip the ckill check

Do some quests for the Followers. Eventually, you can ask Arcade to join you without having to succeed in a Speech challenge.

Confirmed Bachelor.