A few more from Gens 7 and 8:
Comfey is holding a ring of flowers.
Oranguru is holding a fan made of leaves and fur.
Passimian is holding some sort of berry.
Sandygast has a shovel stuck in its head.
Palossand has a shovel stuck in its head.
Komala is holding a log. (There are theories that the log is Komala -- so maybe Komala is holding a koala.)
Dhelmise is holding an anchor.
Grookey is holding a stick.
Thwackey is holding two sticks.
Rillaboom is holding two sticks and a drum.
Skwovet is holding berries in its mouth.
Greedent is holding berries in its tail.
Flapple is holding an apple as a shell (debatable)
Appletun is holding an apple as a shell (debatable)
Cramorant sometimes holds Pikachu or Arrokuda.
Sinistea holds a teacup (technically hides in it, but close enough)
Polteageist holds a teapot (technically hides in it, but close enough),
Sirfetch'd is holding a leek shield and a leek sword.
Mr. Rime is holding a walking stick.
Drakloak holds a Dreepy.
Dragapult holds two Dreepies.
Zacian Crowned Form is holding a sword.