Specifically in countries that gained independence from Austria, Russia, and Germany during/after WWI, such as Poland, the Baltic states, Czechoslovakia, and Hungary. We're these countries mostly dictatorships like Germany, Spain, and Italy? Or were they better able to form stable democratic governments?
I'd also be interested in the situation in the previously Ottoman states, Bulgaria, Romania, Greece, and Yugoslavia.
Between 1918 and 1943, Yugoslavia was made up of former Ottoman and Austrian territories. It encompassed all of what would become the Socialist Federal State of Yugoslavia except for the Free Territory of Trieste, which included parts of the Slovenian littoral and Croatia.
Between its genesis in 1918 and 1921 politics were contentious. Because Serbia had experience with independence before WWI, they had many of the trappings of a state: a military, a police force, experienced politicians, etc. Naturally, many Serbs pushed (as well as members of other ethnic groups) for centralization. This was led by the the largest political party: the Democratic Party. They were opposed by the Croatian Peasant Party, who opposed the centralization efforts. The Democrats sought a partnership with the Social Democrats, who favored centralization, but opposed the anti-communist bent of the Democrats. New elections in 1920 did not provide a clear winner, as the Democrats lost a lot of ground, but without any single member of the opposition picking up the pieces.
On June 28, 1921, a unitary monarchy was established in a new constitution. Shortly after, King Peter 1 of Yugoslavia died (August) and King Alexander 1 took the throne. During this time, battles in parliament took place, largely on Serb vs. Croat lines. Many Serbs saw Yugoslavia as a project for a greater Serbia, and were bitterly opposed by the Croats (second largest ethnicity.) Prime Minister and Serbian Nationalist Nikola Pašić began repression of the opposition throughout the 1920s, seeking to influence elections with force to increase the Serbian majority. On June 20, 1928 a deputy in Pašić's own Serbian Radical Party shot 5 members of parliament in the opposition Croatian Peasant Party, two of whom died on the floor. Fearing for their lives, the opposition withdrew from parliament.
As a result of the political crisis, King Alexander abolished the constitution on January 6, 1929, and established a dictatorship. There were elections, as executive power was to be a gift of the king, but there was immense pressure for the majority. Many opposition politicians were arrested, killed, or went into exile during this time, particularly Croats.
The foreign policy of the Kingdom of Yugoslavia under both Alexander I and Peter II was characterized by close relations with the allies of WWI, and they also formed the so-called Little Entente with Czechoslovakia and Romania, supported by France. Because of territorial disputes, they were opposed to Mussolini's Italy. However, due to France's weakness (Yugoslavia's closest friend among the allied powers) they were unable to stand up forcefully against the Germany and Italy, especially due to economic reliance on Germany. They tried to remain neutral, but could not fend off German invasion.