pioner

/pioner/

Cases

SingularPluralWhen to use it
nominativepionerthe Pioneerpionerlethe Pioneersthe plain dictionary form — the doer of the sentence
genitivepionernithe Pioneer'spionerlenithe Pioneers'the owner — whose it is
accusativepionernithe Pioneer (as the object)pionerlenithe Pioneers (as the object)a specific, known object — whom or what
dativepionergeto the Pioneerpionerlegeto the Pioneersdirection or recipient — to where, to whom
locativepionerdeat / in the Pioneerpionerledeat / in the Pioneerswhere it is; also having — mende bar, "I have it"
ablativepionerdenfrom the Pioneerpionerledenfrom the Pioneerswhere it comes from; also "than" when comparing
When to use each case
nominative
the plain dictionary form — the doer of the sentence
genitive
the owner — whose it is
accusative
a specific, known object — whom or what
dative
direction or recipient — to where, to whom
locative
where it is; also having — mende bar, "I have it"
ablative
where it comes from; also "than" when comparing

The endings are the same ones the pronouns wear — that page explains when each case is used.

With an owner

One ownedSeveral owned
mypionerimmy Pioneerpionerlerimmy Pioneers
yourpioneringyour Pioneerpionerleringyour Pioneers
his / herpionerihis / her Pioneerpionerlerihis / her Pioneers
ourpioneribizour Pioneerpionerleribizour Pioneers
you all'spionerigizyou all's Pioneerpionerlerigizyou all's Pioneers
theirpionerleritheir Pioneerpionerleritheir Pioneers

The overlap in the last rows is real, not a mistake: pionerleri can mean "his / her Pioneers", "their Pioneer", or "their Pioneers" — context decides.