Tails witnesses Metal Sonic beating up Sonic at the beginning of Sonic Forces.
This section is in need of major improvement. Please help improve this article by editing it. Tails was present with Sonic and Knuckles when Dr. Robotnik introduced Hyper Metal Sonic to the trio. Tails and Metal do not interact with each other much like Sonic does, but was able to partly control Metal's internal systems, only to have the controls destroyed by Robotnik. The fox later witnesses Hyper Metal Sonic rescuing the President and Old Man Owl after Sonic overloaded the robot and pushing him into to the rocket's cockpit.
This section is in need of major improvement. Please help improve this article by editing it.
In the opening of Rise of Lyric, Eggman commands Metal Sonic to hunt down Sonic and the rest of his team. Eventually, the four are cornered by a robot army as they tried to enter Lyric's tomb. After a small fight with the army, Metal Sonic appears from the sky and punches the ground, the resulting impact pushing Tails, Amy, and Knuckles back. As Metal and the army close in on the team, Sonic opens the tomb, calling on his teammates to get inside. Later on, Metal Sonic (under the control of Lyric) steals a Chaos Crystal but Team Sonic were able to shut him down.
In the part two of "Eggman: the Video Game", Shadow and Sonic jump through the portal back into the Sonic Boom World with both hedgehogs carrying Metal. The fight continues into the village, with the rest of Team Sonic (Sticks included) joining in later. Amy saves Tails from falling debris after Metal shoots a laser at Shadow, pushing the black hedgehog and Eggman back towards a wooden building. With Metal Sonic gaining the upper hand after taking on Team Sonic, Sonic uses an Enerbeam to bind Metal, with Tails and Knuckles following suit. When Metal prepares to fire at a recovering Amy, Sticks disables the robot with her staff. After Shadow threatens to end the world (since both Eggmen are in the same dimension), Tails reprograms Metal to activate a homing beacon that tracks Eggman's current location, after which Sonic follows the robot on his Blue Force One.
Tails (playable by himself or as Sonic's companion) fights Metal Sonic at the end of Stardust Speedway Zone Act 2. After destroying a Metal Sonic Projector and releasing his (their) animal friends, Metal appears. The robot chases him (them) as they lead to an arena. Inside, Metal Sonic controls a generator that dispenses Silver Sonics. Tails (or Sonic) uses these robots to hit Metal; after a few hits, the generator is destroyed and the chase continues. It ends at the top of the zone where a large Eggman statue is on the background. They "race" around the statue against Metal as a spiked wall pushes behind them. Eight hits on Metal Sonic defeats him, breaking the spiked wall.
In Sonic Mania Plus, the chase goes the same way, but this time after reaching the top, Dr. Eggman on his Eggmobile throws the Phantom Ruby to Metal, the latter transforming into Giga Metal. Shattering the container that encloses the Ruby eight times destroys this form, defeating Metal Sonic.
In "Metal Mayhem", Sonic and Tails enter Dr. Eggman's lair. They were stopped by Metal Sonic, who traps them and takes their acquired Chaos Emeralds off their hands. Sonic fights the powered-up Metal Sonic while Tails cowers in fear. The hedgehog is later teamed up with Ray and Mighty, giving Tails motivation to fight Metal with them. However, they were no match for the robot. Tails uses Eggman's remote control, calling on Sonic to lure Metal to one of the traps they fell to at the beginning of the episode. They succeeded, releasing all seven Chaos Emeralds out of Metal's body. Defeated, Eggman reveals the Master Emerald from the floor and empowers Metal Sonic with it. Knuckles interrupts Metal's transformation by punching the robot, the resulting impact pushing both Metal and Eggman out of his own lair.