Claiming a Username for Your Bot
When you register a bot, you should choose its username carefully. It will be difficult to change it afterwards.
How should the username look
Bot usernames are no different from usernames of users, groups and channels. The only constraint is that a username of a bot must end with "bot."
A username can look like this: @ExampleBot
There are official bots with special usernames that don't follow the form: @pic, @vid, @sticker. Also, you can now buy short usernames on Fragment.
Many usernames are taken
A free username must contain at least 5 characters including "bot." However, you can't claim such a short username: all usernames of 5 (and maybe 6) characters are taken.
Unfortunately, all these registered bots are mostly dead. Developers rarely support bots for a long time :(
You can claim a short username through the support
It is possible to change a bot username for free, even if it's claimed by another (inactive) bot. You will need to contact the support: @BotSupport. They will check whether your bot works and supports English language.
The common format is the following:
1. @old_username
2. @new_username
3. Some bot description
1. @old_username
2. @new_username
3. Some bot description
Then cross your fingers and hope the support won't ignore you.