What you need to understand is that Digimon are almost biologically the same throughout all the series and thus they should share the same dietary habits as each other despite being from different series. Also, do not treat food in the digital world really as food, they are data. Therefore, when a materialised Digimon eats human food, they can taste it and enjoy it, but not grow from eating it.
For a Digimon to grow/digivolve, they consume data and train, which in turn 'upgrades' their own personal data, gain experience and level up if you will, as demonstrated by Tactimon in When Worlds Collide saying that he trained in order to evolve and grow and when he absorbed the data from the human world, he grew more powerful. Keramon from Digimon Adventure also acts like Tactimon to a certain degree, consuming data until he digivolves into Chrysalimon.
Digivolution for Digimon is similar to aging for humans—it is generally a one-way journey whereby a Digimon will grow into a new form as they age and gain battle experience and data. However, moving from one form to another becomes progressively more difficult. Therefore, very few Digimon will ever naturally digivolve into their final most powerful forms.
This establishes the premise that in order for a Digimon to grow, they need data and since their whole world is made of data, they can just eat their surroundings, but of course, this is rather useless as small bits of data does not provide any use in growing as shown by Beastmon consuming Tyutyumon but not digivolving. But of course, if you eat enough, like Lucemon from frontier, who consumed the whole digital world and all its inhabitants, you become all powerful. However, not all data are edible in Tamers as shown by Guilmon in Goliath.
Sorry if I digressed too much but in conclusion, YES, Digimon do eat other Digimon for their data in order to grow more powerful as all the data you consume from the other Digimon upgrades your own data. The reason why Digimon opt to eat other Digimon as a Digimon provides more data then eating regular, more common forms of data, such as grass.
Smaller Digimon are incapable of preying on other Digimon effectively as hatchlings contain very little data and are often protected by powerful Guardian Digimon so the most common predator species are at least Champion Level or higher. Some examples include MachineDramon and Arukadhimon from Xros Wars.