Any "as [this permanent] enters the battlefield" or "[this permanent] enters the battlefield with" abilities of the copied creature will also work
Amazing Acrobatics will counter a spell and/or tap one or two creatures
There are plenty of commanders with a tap ability that could really use haste, and its also terrific with the sorts of commanders that need to attack in order to trigger some nifty bonus
Temmet, Naktamun's Will boosts every Zombie creature, and since it's a Zombie itself, it will also give itself the stat boost with its effect
Magus Lucea Kanes doubling up of X-cost spells, and the Swarmlord turning your creatures with counters into card draw, means there are some really fun strategies here - Tyranid Swarm is a deck that truly does feel like a swarm, and can give you big creatures to attack with, and plenty of tokens back to defend if youre smart
Partner is a very controversial mechanic in Commander and has had a tremendous impact on the format ever since its introduction in 2016