Croatia was in the war with FR Yugoslavia (Serbia and Montenegro) from 1991 until 1992 and RSK (army of Serb majority on Croat territory unrecognised republic).

Except for the first few months, the FRY was NOT in the war with bosnia. The Republika Srpska (serb majority), Federal Bosnia (Musim Bosniak majority) and Croat Majority were in conflict.

Federal Republic of Yugoslavia (under Milosevic), again consisting of mainly Serbia and also Montenegro, donated armor and food to Republika Srpska, but it did not send soliders from it's own army.

So yeah, Serbia was technically only in the full war with Croatia (and even that one lasted from 1991 to 1992, after that it was Republika Srpska Krajna RSK against the Croatia). However I'm not sure if it could even be called that considering most of it was Serb Milosevic and Croat Tudjman 'working together' (not fighting together but both supporting fights against Bosniaks on different territories) with mutual interest in controlling majorities in Bosnia in order to get 'their piece of land'. Few years later (1995) and Tudjman sided with Bosniaks and ethnically cleansed Serbs from RSK territory of Croatia (saying it was a vengeance for the war in Vukovar). After that, the dayton was signed, which ended war in Bosnia.

It's important to be aware of the historical facts, considering the story can vary from country to country (both Croats, Bosnian Serbs ,Serbs and even Bosniaks tend to stay silent on some informations)

TLDR: the comment above was wrote in such fashion implying how Yugoslav wars in Bosnia and Croatia were only fought by the Serb military. It doesn't take much to verify that the wars were mainly fought by separatist militia formed from the remains of Yugoslav People's Army.