Create bulleted list in iOS Mail
Solution 1:
Until Apple offers the ability to add some basic controls (eg. bold, etc.) on the iPhone/iPad (without the keyboard) it's not possible without copying and pasting from a previous message.
You could create a draft with the different types of list to copy and paste and use that.
Of note: some third party apps can help with this: eg. MarkdownMail just released today by Second Gear Software ($1.99) or any other app that will allow you to create HTML.
Solution 2:
It’s a hack, but one thing you can do is compose your message in a note, which does support bulleted lists, then copy the message into the email app. It really surprises me that this feature doesn’t exist.