I’d like the middle name to be [name_m]Earl[/name_m].
I’m not a fan of [name_u]Theo[/name_u], or any [name_m]Ed[/name_m]- names.
I’ve considered [name_m]Thaddeus[/name_m], it sounds good with the middle name [name_m]Earl[/name_m], but I’m not sure about it any more. I’d love your thoughts on [name_m]Thaddeus[/name_m].
I’ve recently fallen in love with [name_m]Theodore[/name_m], but is it too awkward sounding with [name_m]Earl[/name_m] as a middle?
My personal favorite way to get to [name_u]Teddy[/name_u] is [name_m]Thomas[/name_m].
Not really an usual option, but I think [name_m]Thomas[/name_m] nn [name_u]Teddy[/name_u] works 
[name_m]Thomas[/name_m] [name_m]Earl[/name_m] doesn’t sound too bad either, I think.
[name_m]Theodore[/name_m] or [name_m]Thaddeus[/name_m].
The nice thing about [name_u]Teddy[/name_u] is that there are a lot of options!
Personally I really like [name_m]Theodore[/name_m] and don’t think it sounds awkward with [name_m]Earl[/name_m] at all - however, if you don’t like [name_u]Theo[/name_u], it might not work as people nearly always naturally shorten [name_m]Theodore[/name_m] to [name_u]Theo[/name_u], so you’d have to specifically tell people that his familial nickname is [name_u]Teddy[/name_u].
On the other hand it does depend on how much your using [name_u]Teddy[/name_u]; whether it’s just a nickname, or a name he would actually go by the majority of the time. If you just plan on calling him [name_u]Teddy[/name_u] the whole time, and just want a more formal name to put on the birth certificate, than [name_m]Theodore[/name_m] is a great choice I think.
[name_m]Thaddeus[/name_m] is also a very nice name, though to my ears it does seem a tad formal/biblical in a serious sort of sense, so again I think it would work best in the second of those two circumstances.
A couple of further ideas I had:
Perhaps you could look at some of the more literal interpretations of the name [name_u]Teddy[/name_u]; [name_m]Bear[/name_m] is often put on birth certificates, and I think it’s very cute, though admittedly doesn’t fit the style of the other names you said you liked.
Alternatively you could look at different variations of [name_m]Theodore[/name_m]; I thought of [name_m]Theodoric[/name_m], mainly because the different stress pattern lends itself away from the [name_u]Theo[/name_u] nickname.
Additionally I do like the [name_m]Thomas[/name_m] suggestion - I wouldn’t have thought of that but it does work quite well!
In the end though I did want to say that it’s perhaps worth considering just giving him a name you like for his full name, that’s not necessarily related to [name_u]Teddy[/name_u]. I mean, [name_u]Teddy[/name_u] is pretty far from [name_m]Theodore[/name_m] anyway…
I like [name_m]Thaddeus[/name_m] [name_m]Earl[/name_m] the best. But [name_m]Theodore[/name_m] is one of my favorite names. [name_m]Thomas[/name_m] is a nice compromise.
I think I would use [name_m]Theodore[/name_m] and find a different middle or not worry about it as one seldom uses all 3 names together and if you want [name_m]Earl[/name_m] for an honor purpose - I would just use it.
Hm. Let’s see.
[name_m]Theodore[/name_m] [name_m]Earl[/name_m]
[name_m]Thomas[/name_m] [name_m]Earl[/name_m]
[name_m]Thaddeus[/name_m] [name_m]Earl[/name_m] (feels a bit stuffy)
[name_m]Taiden[/name_m] [name_m]Earl[/name_m]
[name_m]Tanner[/name_m] [name_m]Earl[/name_m]
[name_m]Theodore[/name_m] and [name_m]Thaddeus[/name_m] are both gorgeous, but I’d go with [name_m]Thaddeus[/name_m] if you’re really set against [name_u]Theo[/name_u].
[name_m]Thomas[/name_m] is nice but a bit bland next to your other choices.
What about [name_m]Earl[/name_m] [name_m]Theodore[/name_m]? And he could still go by [name_u]Teddy[/name_u]?
I love [name_m]Thaddeus[/name_m] and [name_m]Theodore[/name_m]. [name_m]Thaddeus[/name_m] [name_m]Earl[/name_m] sounds great. I definitely think [name_u]Teddy[/name_u] can work as a nickname.
I’m not loving how [name_m]Theodore[/name_m] [name_m]Earl[/name_m] sounds. Plus, as he gets older, he will most likely be called [name_u]Theo[/name_u] by some people. I personally love the nickname [name_u]Theo[/name_u], but if you don’t like it, then maybe it’s not the best choice for you.
I was looking up names that mean bear and [name_m]Arthur[/name_m] popped up. [name_m]Arthur[/name_m] [name_m]Earl[/name_m] doesn’t sound great, though. [name_u]Barrett[/name_u] means bear strength.
Wish I could help more, but I really do like [name_m]Thaddeus[/name_m] [name_m]Earl[/name_m].
Both are two of my favourite names!!! (see signature for proof)
I think if you want [name_u]Teddy[/name_u], [name_m]Theodore[/name_m] is the better option - when I’ve tested [name_m]Thaddeus[/name_m] with friends, they all said [name_m]Tad[/name_m] or [name_f]Addy[/name_f] were the more logical nn (which makes me sad because I love [name_u]Teddy[/name_u]!!).
[name_m]How[/name_m] about [name_m]Thierry[/name_m]? Or, my OH’s name, which is [name_m]Terence[/name_m]? He used to go by Ted when he was younger.
Another possibility is [name_m]Frederick[/name_m]; it may sound strange as a full-name option for [name_u]Teddy[/name_u], but it does have some literary credential, being the full name of a character who goes by [name_u]Teddy[/name_u] in [name_f]Emily[/name_f] of [name_m]New[/name_m] [name_f]Moon[/name_f]. I quite like it myself.
I love love love the name [name_m]Theodore[/name_m]. [name_m]Thaddeus[/name_m] is also a great name.
Ted [name_u]Kennedy[/name_u] was formally [name_m]Edward[/name_m]! Perhaps [name_u]Teddy[/name_u] can be a nn for an “ed” name if you like that sound more than you like [name_m]Theodore[/name_m] or [name_m]Thaddeus[/name_m]!