Flowey is similar to his Undertale counterpart, other than the various rips and tears in his body. Over the course of the game, they slowly heal until he looks much more like his original self.
Much like his Undertale counterpart, Flowey is still obsessed with power and controlling the timeline. However, he does not let this show, putting on a cheery attitude to get on the player's good side. However, he doesn't have the best temper and is not afraid to fight, should anything go wrong. Once he has become a good friend of the player, progress is a larger priority to him than his safety, as despite him having little to no control over the timeline, he knows Frisk will reset should anything happen to him.
Flowey is able to to see any monster's stats, as well as judge their EXP and LOVE. He has information on all monsters and knows everywhere in the underground. He can use roots and vines as arms, and burrow underground to move. He is able to use his friendliness pellets in battle, and can use both white and green attacks..
After meeting the human, Flowey teaches them the core fighting mechanics, as well has how the menu works later on. He is able to read a monsters stats including their EXP and LOVE for the player, and give them first-hand information on them. He uses his knowledge to guide the player through the ruins, and to a lesser extent, the rest of the underground.
Flowey is an enemy to Toriel, who has hurt and threatened him multiple times for attacking prior humans. They are able to get along in each others presence while the player is around, and Flowey can even acknowledge her usefulness, but overall dislikes her.
Although Flowey doesn't trust Sans, since Sans has caused him a fair amount of trouble in previous resets, he realizes how useful Sans can be and acts friendly toward him. Since Sans was involved in the events of the true lab, Flowey suspects Sans knows who he is, but Flowey tries to not bring it up.
Flowey does not have much of a connection with Alphys, other than Alphys being involved in the creation of him.