I have no idea what kinds of overlap we have between /pokemon and /tf2, but it sounds like there's room for pkmnjokeexplainer here.

Team Fortress 2 is a class based objective oriented multiplayer FPS. Capture the flag, attack/defend, capture and hold.

This picture depicts cp_steel, a control point or attack/defend map. Blue team must attack attack 5 control points and hold them for a period until it is "captured," at which point they can push on to the next point. Red team's goal is to stop them. Hence the title, "Cap Them All."

This is the last control point on the map. As the defending team Chansey, Joy, and Jenny are holding the last point to prevent a capture and loss of the round. Note that when a member of team Red is physically on the point Blue will be unable to capture and must dispatch said Red team member first. They are exhibiting best practices by fighting on the point. Except for Jenny. Snipers should only be on point as a last resort. What are you doing Jenny, get out of there.

The three classes here are:

Heavy (Chansey): A high health tank (is Chansey still a good wall in B/W?) type character with an iconic minigun that deals heavy damage at close to mid range.

Medic (Joy): A support class that focuses on on healing friendly players. Also has the ability to periodically turn herself and the team member she's healing invulnerable for 8 seconds. Heavy's high health makes them a great partner for Medics (as shown).

Sniper (Jenny): A sniper is a sniper. Special weapons are obviously the sniper rifle. The rifle deals more damage the longer it is scoped in and leaves a visible designator dot. Note that the laser-like trail in the back is colored red. That's the laser trail of another (friendly) sniper. Sniper's can also fill a jar with urine and throw it at enemy players to increase damage dealt to the target. Alternatively they can throw it at friendly players to extinguish fires set by Pyros (another class).

Pokemon not included.