#3 To tease him as a potential Brock Lesnar opponent

The consensus seems to be that the man who eliminates Brock Lesnar at the Royal Rumble will be the one to face him at WrestleMania 36. Whether they beat him or not is yet to be seen.
There are a few candidates for that role, with Drew McIntyre being one of the favorites. While Roman Reigns is believed to be one of the favorites to win the Royal Rumble, him eliminating Brock Lesnar seems unlikely as it's both pointless and serves no purpose since they're not revisiting that feud.
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The man who eliminates Lesnar doesn't even need to win the entire Rumble match. The second-last spot would be ideal but having a good showing would be enough. The confrontation with Ricochet was perhaps to tease the idea of The One and Only superstar being the man who eliminates Lesnar.
With that being said, we don't believe Ricochet is ready for that spot just yet. He will be, without a doubt - just not right now.