The standard hydrogen nucleus is a proton. There are also isotopes that have a neutron or two in addition to the proton. Since even the biggest elements do not have a neutron to proton ratio greater than 2:1, fusing hydrogen atoms over and over could concievably make up any other nucleus.
However it's not true that
...all other elements (100+) in the Periodic Table are made from Hydrogen...Like, variations of Hydrogen nuclei in those atoms
because a hydrogen nucleus consists of exactly one proton. Helium's nucleus with it's two protons is not a "variation of a hydrogen nucleus" because it does not contain exactly one proton.
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