It will vary team to team.
You have true professional teams such as Russian legion.
It is their full time job and they constantly practice
They will use specific gear
You also have teams that will turn up to play at the weekend and that's that.
If they have sponsorship it will just be an agreed discount, so you can buy from that retailer if you wish
Their performance may differ from teams that regularly practice though!
There are many factors to joining a team - do you fit in wih them, can you play 'well to their standards', or perhaps you are fresh blood ready to be moulded into their needs, do your commitments meet the teams
If 'only weekends' are suitable to the team it may backfire when your family realise you are never around. Or they may be delighted!
Another option is to check around the school for others interested in paintball and to start a school team
There are also other flavours of paintball, and being in a team is not essential
If speedball style is your preference then a team is the ultimate way to go
But you can do walkons and turn up alone or with a couple of mates, once you have been a few toones the regulars will be your mates
Some events do 'scratch' teams of the individual's on the day
You can be different and try scenario with an event somewhere in the country most months. Then you can play alone or tag on with some guys
Scenario teams are usually a group of mates. Regular 'training' is not essential, it's more about having a laugh