Apart of my POD is Ethiopia entering World War 1 on the side of the Entente, receiving professional training and an influx of new military equipment to arm an Ethiopian Expeditionary Force serving in either the Middle East or Europe. Depending on how large it is, the EEF is going to make up the nucleus of a new professional Ethiopian Army under an earlier Haile Selassie and receives additional training under a Japanese Military Mission in the 20s and 30s. This means that Ethiopia could defeat the Italians if such an invasion comes along similarly to OTL - why do you think mostly nothing would change?
With a POD this early, and Ethiopia on the side of the Entente as an active participant in WW1, plenty of stuff's still up for grabs. For instance, an Entente Ethiopia's going to be kept fairly busy, as an active counterweight to both the Ottomans and German East Africa. They're not going to be deployed to Europe- even precluding racism, there's not a chance in hell of that happening, and at that early stage in their divergence from OTL, they'd only get slaughtered anyway. But they would have a very, very good chance of being relatively successful- with Ethiopian manpower on the Entente's side (fighting alongside the Black South African, Indian, and other colonial troops which were considered unsuitable for European service as a matter of racial supremacist policy- who may or may not be more inclined to consider themselves more closely aligned with the Ethiopians instead as a result), it could easily swing the tide in their favor, and force the German colonial forces into surrender, leading to an Allied victory in East African Campaign by 1917. And of course, by then, the Ottoman Empire's already been torn apart by the Arab Revolt of 1916, leaving the Ethiopians (and their Japanese allies and observers) in the perfect position to capitalize and run rampant on the Middle Eastern front.
Only for them to then almost inevitably get treated in the same manner to the Japanese at the Paris Peace Conference, when the Ethiopians send their own delegation there. Course, the Japanese would, courtesy of their greater clout and influence in East Africa and the Middle East, stand a marginally improved chance of being acknowledged as one of the "big five" ITTL, but not by much. Ethiopia would at that stage be the chief occupier of several formerly Central Powers' territories, and would attempt to lay claim to at least a few of them, probably primarily in East Africa and along the North-East coast of the Red Sea. They'd be massively invested in the inclusion of the Racial Equality Clause in the League of Nations' covenant, far more so than the Japanese delegation who proposed it, and they'd be immensely angered at it being thwarted by the Australians, South Africans and British. And even more so than the Japanese, they'd have the door slammed in their faces, and all of those German and Ottoman overseas possessions they'd liberated and occupied stripped away from them, to be awarded as "mandates" to the British Empire, France and quite possibly Italy instead.
For Ethiopia, this would have an immediate impact, driving them away from cooperation with the West and toward more nationalistic policies (such as Pan-Africanism) even more than it did the Japanese. And it'd definitely cement their alignment with the Japanese. Along with cementing Japan's (fairly ironic) perceived status as the world's primary proponent of racial equality, and probably setting into motion a feedback loop which would make TTL's post-WW1 'Yellow Peril' in the African, Middle-Eastern and even Indian colonies even worse than the Red Scare IOTL, and far longer lasting; and which, in turn, would make Ethiopia's Pan-African ideology increasingly nationalistic, militaristic and fascist in nature as well. How would this Japanese-Ethiopian alliance end? Most likely, with the Stresa Front forged with the threats posed by both Germany in Europe and the Japanese-led Co-Prosperity Sphere's expansion beyond East Asia into East Africa, via their alliance with the Ethiopians, in mind. And with both the British and French either maintaining their neutrality, or joining in with Mussolini, in invading Ethiopia.
If it's the latter, barring a miracle (or plot-induced suicidal tendencies), the Japanese only put up a token resistance, and the greatly improved Ethiopia still gets rolled over ITTL, partitioned between the three Colonial Powers, thereby becoming a martyr for the Japanese cause and enabling them to drum up far greater support from those advocating independence from the Western Colonial Powers; but if it's the former, and Ethiopia has grown powerful and influential enough by this stage, and manages to repel the initial Italian invasion force, then it might not only be the Japanese who rally to their side, and join them in declaring war against Italy. IOTL, Hitler's Nazi Germany was the only nation to provide the Ethiopians with material support in the 2nd Italo-Ethiopian War. ITTL, with the Spanish Civil War yet to get under way, mightn't he potentially join in to an even greater extent, sending the Condor Legion over to fight on the Ethiopians' side? And if so, couldn't such a conflict have had the potential to kick off an alternate, earlier WW2...?