They look like and are based on regular items. Their short descriptions are the same as their counterpart item, but have "...?" at the end. However, they have differences in their names (usually subtle spelling changes) and will have different effects; sometimes it is the opposite effect of the item it is imitating. Their full descriptions are also different.
List of Lookalike Items
Oren Berry オレソのみOreso Fruit
A food item that deals 10 damage and restores Belly by 5. Lookalike for Oran Berry.
An item that revives a fainted Pokémon...right? And after reviving? It becomes a Plain Seed after use. It can only be used by a Pokémon that knows the Item Master IQ Skill. It is a Lookalike Item for the Reviver Seed, so be careful!
Via Seed じゃあなのタネSee-ya Seed
Cannot be bought
Makes the user say "See-ya!" and warp to a different place on the floor. Restores Belly by 5. Lookalike for Vile Seed.
A food item that gives the Slip status, where it is possible to walk on water. It also somewhat fills the Pokémon's Belly. It is a Lookalike Item for the Sleep Seed, but you'll be pleasantly surprised when you make a mistake on this one!
A drink that restores the PP of all moves, but only for Linoone. It also slightly fills the Pokémon's Belly. It is a Lookalike Item for the Max Elixir. Remember, it can only be used on Linoone, so be careful!
This item has a nostalgic feel and causes the user to bring to mind a dearly held memory When this item is used, tears begin to well up, and the user sobs and switches to Enduring status. A Lookalike Item for Geo Pebble.
The Gravelyrock is very hard, rock-like candy. When eaten, it somewhat fills the Pokémon's Belly. It permanently raises the IQ of a team member. It only affects Bonsly and Sudowoodo. It is a Lookalike Item for Gravelerock, so be sure to check carefully before using it!
A held item makes the Pokémon stand out, making it easier to hit by enemies. It looks a lot like the Goggle Specs, so be careful not to confuse them!
Y-Ray Specs みおとしメガネOversight Glasses
Cannot be bought
Disables the ability to see items and enemies. If held by an enemy or an ally, they will receive the Blinker status which causes them to walk forward in a straight line and attack if it cannot move any further. Lookalike for X-Ray Specs.
When the leader is holding this, items and enemies won't appear on the map. If anyone else holds this, they will be affected by the Blinker status. It looks a lot like the X-Ray Specs, so be careful not to confuse them!