I’ve had tutus, super hero costumes, as well as suits and ties! Just pick something that your happy to get messy! I would also recommend dressing in something comfortable yourself as you are sure to get covered in cake too.
The cake must be supplied by yourself, but I’m happy to point you in the right direction to a great cake maker. I have plenty of buntings to hang, but if you are after a certain colour it might be a good idea to bring one along.