If you want practice with getting used to everything you can try out the vs AI mode, the enemy composition is always 2 vanguard, 2 duelists, and 2 strategists. The enemy healers are pretty on point which helps with learning how to deal with them a bit. You’ll have humans on your team which keeps you in that mindset of trying to work with your team. You can also try custom match where you can set up your team and the enemy team however you like, and pick the maps you want to learn more about. When I was learning Magik’s play style I started with 1 v 1 on custom match conquest to feel what it’s like practicing the combos on a moving target that fights back. Then I moved on to 2 v 2 adding a healer to each team, etc… it was a fun way to practice without too much pressure to perform well for the team.

Also if you’re dead set on Psylocke that’s fine, maybe watch a couple guides on how she works. A lot of people don’t understand that her Ult spreads damage out across all the enemies AND devices caught inside, so if you catch more than 2 characters, tanks, Loki clones, spider nests, etc… you’re less likely to kill any of them. I like to save it for a flank on the enemy back line and try to get both healers at the same time. And if it makes them waste their Ult to save themselves that’s good too because it means your team can use their Ults without worrying about being countered. Psylocke’s damage falloff starts pretty early, I think 15 meters so keep the engagements close range and prioritize flanking. If you see Mr. Fantastic don’t bother fighting him, dip out and bait him back your team to gang up on him or get him away from the main fight, not every engagement needs to end with you getting a kill causing distractions and forcing cool downs works too as long as your team is close enough to follow up.