Not quite. First, the "EM fellowships" are one year. They don't lead to any guarantees that you'll be hired on par with a residency trained EM doc. Also, having done IM, instead of FM, will leave you at a disadvantage, since you'll have no Ob/Gyn, surgery, or peds experience, and minimal psych.
There is no "qualification", per se, to work in the ED. When I worked in SC, the Chest Pain Center was mainly staffed by IM docs - and that's all they did. Also, since they weren't EM-trained, they weren't eligible for partner. When I say "no qualification", I mean you can do any job for which the hospital credentials you. That doesn't mean you can do it well.
Alternatively, if you really really want to work in the ED, you could go to a rural, rural place. A residency classmate had done a transitional year, then a year of IM, and was working in an ED in Idaho, before coming to EM residency.
These are just the vicissitudes of what you ask.
