Anything bred in ireland to be honest. Though it is most likely to be at least part Connemara, often with Thoroughbred and/or Irish draft blood. Some have welsh blood too or arab -theoretically they can be any crossbred bred in ireland. However, there arent many common breeds in ireland apart from TB, Connie, ID and nowadays continental warmbloods.
I have an Irish pony registered as an Irish sports pony too, if its the dun in your sig, then hes got some definate connie traits, probably crossed wih another irish sports pony.
usually connemaraXtb or draft a few cross' down the line can be called ISH though they often arent offically registered
...the skewbald in my siggy is down as an ISH on his passport hes only likely to make 13.2 is 13.0 at rising 3 and i sincerely doubt he any tb in him more likely trotter,cob.connemara etc
the bay is a connemara cross and also down as an ISH 2 shes around 13.2 14 hands at rising 2 so there is plenty of scope with the "breed"