It depends on what Alex Bregman does, but these teams are excellent fits.
Every team in this section would be a good fit for Nolan Arenado, he's been reported to have interest in playing for them, and they've been rumored to be interested in him, too. However, Nado's inclusion on these rosters depends entirely on what free agent Alex Bregman does. These clubs have a need, and Arenado has an interest. Stars still need to be aligned.
New York Mets
In the case of the New York Mets, a trade for Nolan Arenade depends not just on what happens with Alex Bregman, but also what happens with Pete Alonso. If the Mets are unable to sign either, Arenado can play third base in Queens, and Mark Vientos can move to first. If the Mets sign either Bregman or Alonso, they're out of the running for Arenado.
It's clearly a win-now (and for the next decade) situation for the Mets after they signed Juan Soto. Francisco Lindor, Starling Marte, and Francisco Alvarez round out a balanced lineup for the Mets. Where New York probably needs to make acquisitions still would be in the rotation, but adding a player of Nolan Arenado's level wouldn't hurt one bit.
Also, who wouldn't want to hit with Lindor and Soto in the lineup? Arenado would bring balance to their lineup, experience to the clubhouse, and a Gold-Glove pedigree to their defense. He and Lindor would again make for a potent left side of the infield.
Toronto Blue Jays
It seems as though the Blue Jays have been grasping at straws for two years now. They've missed out on free agents like Shohei Ohtani, Carlos Correa, and Juan Soto to only watch the primes of players like Vladimir Guerrero Jr. and Bo Bichete pass with nary a postseason success story to share.
The Blue Jays may become desperate for a big swing and opt to trade for Nolan Arenado, but they probably prefer Alex Bregman. If Toronto once again loses out on a big-name free agent, their desperation may push them back to John Mozeliak and a trade.
With Vlad Jr. and Bo Bichette set to be free agents after 2025, the Blue Jays could aim to make a huge push for the playoffs this year. Adding Nolan Arenado at third, a place formerly occupied by Ernie Clement and his .692 OPS, would help their cause significantly.
Detroit Tigers
The Detroit Tigers may be one of the best fits for Nolan Arenado. His expanded list of interested teams probably includes the Tigers, and they are a club set to take off next year following a postseason appearance in 2024. They are an extremely young team, as not one starter next year, Javier Baez aside (who may be relegated to the bench), is older than 30. Nado's experience would be welcome on that young of a team.
The Tigers have quite a few lefties in their starting lineup, so bringing Arenado over to provide some balance would be great for their young squad. Detroit has already added second baseman Gleyber Torres this offseason, and trading for Nolan Arenado would provide more pop to the lineup.
Detroit is seen as a favorite for Alex Bregman, and he may be the club's preference. If that falls through, Nolan Arenado is an excellent fall-back option.
Boston Red Sox
The Boston Red Sox have been the team with the most rumors regarding Nolan Arenado all offseason. In fact, Katie Woo reported recently that the Boston Red Sox may be Arenado's last ticket out of St. Louis this offseason.
The Red Sox, similar to the Tigers, are lefty-oriented in the lineup. Arenado's right-handed swing would play quite well at Fenway, as his 1.066 OPS there is fourth-best in all stadiums in his career.
There are some dominoes that must fall if the Red Sox acquire Arenado. First, Rafael Devers must be open to moving to designated hitter this early in his career. If he isn't moved to DH, a move to first base could be in the cards. That would implicate a trade of young first baseman Triston Casas for pitching help.
There are a lot of bridges that need to be crossed and hoops that need to be jumped, but Nolan Arenado being traded to Boston still feels like one of the most ideal routes for all parties involved.