Hi, I was wondering how to add a player with a sidekick class attacked? There doesn't seem to be any available on the select class page.

I then tried to make one of my own but it only has subclasses? Do I need to pay more to unlock this?

Thanks!

I think they appear as monsters? Can I edit them to make them homebrew?

Edit: Wow that's a lot of work to add the echo knight stuff. Is there a reason why we can't have them as normal classes?

As per the very first post in the thread specifically for issues related to Tasha’s Cauldron:

https://www.dndbeyond.com/forums/d-d-beyond-general/bugs-support/87774-tashas-cauldron-of-everything-issues-and-support

Sidekicks

We don't currently have feature support for the sidekicks rules, as presented in Tasha’s Cauldron of Everything. We will be building a proper system to handle sidekicks in a flexible manner.

Quote from Shinshiva >>

 

Edit: Wow that's a lot of work to add the echo knight stuff. Is there a reason why we can't have them as normal classes?

 
The echo knight was from Wildmount, it is available as a subclass if you have purchased it and have Critical Role content toggled on for your character sheet. It has absolutely nothing to do with sidekicks whatsoever.

Sidekicks are not available as normal subclasses because they are not normal subclasses. They are not presented as a player option. They are for NPCs.