in Red, I would add Legendary Ike, because with the pretty regular bonus stats and Light season he can actually reach pretty solid bulk. As in, when Light and Earth intersect. I don’t personally think he’s an amazing tank per say, but he’s alright and I’ve seen him moderately often. I would also add on Julius for Red - I know there’s a few of them out there, and he’s actually a really solid Red tank if you play him right, especially in Astra.
For Blue, I would add Sharena, since while not many people actually run her, she’s a very viable option that I’ve heard is actually used somewhat in high AR, though I can’t prove or refute that. But she relies on the bonus stats during her bonus season and essentially operates the same as Donnel. Fjorm I see quite regularly being a tank, ranging from base kit to maximum investment. I myself use her with DD4 and Null C-Disrupt, though I need more merges so she has less struggles vs fast enemies.
For Green I’d add Myrrh because I see her actually semi-regularly, and her breath effect is incredibly potent and keeps her from having the same speed struggles as somewhat slower tanks. She otherwise operates somewhat similar to Fae but perhaps less flexible because she can’t deal with Bows or has to sacrifice seal for Iote.
For Colorless you pretty much got them all.
The units on this list that I’ve never in my life seen as an omni tank, like, not even once are L Marth, Felicia, Saizo, and HS Camilla. Felicia and Saizo seem perhaps too reliant on having their respective mythical units, or just aren’t popular enough, and presumably the same case with HS Camilla (who usually is better with Vantage anyways from what I’ve heard).