Is Rotom a legendary?

No

It's a rare pokémon, just that.

no

Rotom are not a legendary Pokemon, but they are rare.

In Pokemon Adventures, Rotom is a legendaryPokémon. It first appeared at the Old Chateau 

No there not but there sort of rare

It was never a legendary Pokemon, it's only a rare Pokemon.

No its not powerfull enoght, its just rare. It is also able to breed with a ditto, the only legendary cappable of that is manaphy

If my memory serves me correctly, Rotom happens to be a rare Pokemon. That's all

If I recall correctly Rotom isn't a legendary,however it is a rare Pokemon.

Nup, it's just rare.
If it was legendary, it would probably tell Du in-game, and give Du a fair shot at catching one, like other in-game Legendaries. Out of all the Pokemon games I've played I've never seen oder caught one, but yeah.
They're just...rare.