Chakram Slinger — ruling 1

"Partner with [name]" represents two abilities. The first is a triggered ability: "When this permanent enters the battlefield, target player may search their library for a card named [name], reveal it, put it into their hand, then shuffle their library."

Chakram Slinger — ruling 2

Note that the target player searches their library (which may be affected by effects such as that of Stranglehold) and that the card they find is revealed, even though these words aren't included in the ability's reminder text.

Chakram Slinger — ruling 3

A nonlegendary creature can't be your commander, even if it has a "partner with" ability.

Chakram Slinger : règles, fonctionnement et interactions (MTG)

Chakram Slinger is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Partner with Chakram Retriever (When this creature enters, target player may put Chakram Retriever into their hand from their library, then shuffle.) , : This creature deals 2 damage to target player or planeswalker.

How it works : Chakram Slinger

Original English text — Wizards of the Coast / Scryfall

#1June 8, 2018· Wizards of the Coast
"Partner with [name]" represents two abilities. The first is a triggered ability: "When this permanent enters the battlefield, target player may search their library for a card named [name], reveal it, put it into their hand, then shuffle their library."
No other card is named in this ruling.
#2June 8, 2018· Wizards of the Coast
Note that the target player searches their library (which may be affected by effects such as that of Stranglehold) and that the card they find is revealed, even though these words aren't included in the ability's reminder text.
No other card is named in this ruling.
#3June 8, 2018· Wizards of the Coast
A nonlegendary creature can't be your commander, even if it has a "partner with" ability.
No other card is named in this ruling.

Interactions with other cards

These cards' text mentions Chakram Slinger.

Chakram Retriever

Partner with Chakram Slinger (When this creature enters, target player may put Chakram Slinger into their hand from their library, then shuffle.) Whenever you cast a spell during your turn, untap target creature.